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<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Deciphering the hydrogen-bonding scheme in the crystal structure of triphenylmethanol: a tribute to George Ferguson and co-workers</title><author><name sortKey="Rodriguez Tzompantzi, Tomasa" sort="Rodriguez Tzompantzi, Tomasa" uniqKey="Rodriguez Tzompantzi T" first="Tomasa" last="Rodríguez Tzompantzi">Tomasa Rodríguez Tzompantzi</name><affiliation><nlm:aff id="a">Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author><author><name sortKey="Amaro Hernandez, Aldo Guillermo" sort="Amaro Hernandez, Aldo Guillermo" uniqKey="Amaro Hernandez A" first="Aldo Guillermo" last="Amaro Hernández">Aldo Guillermo Amaro Hernández</name><affiliation><nlm:aff id="a">Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author><author><name sortKey="Meza Le N, Rosa Luisa" sort="Meza Le N, Rosa Luisa" uniqKey="Meza Le N R" first="Rosa Luisa" last="Meza-Le N">Rosa Luisa Meza-Le N</name><affiliation><nlm:aff id="a">Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author><author><name sortKey="Bernes, Sylvain" sort="Bernes, Sylvain" uniqKey="Bernes S" first="Sylvain" last="Bernès">Sylvain Bernès</name><affiliation><nlm:aff id="b">Instituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">PMC</idno><idno type="pmid">31484815</idno><idno type="pmc">6727172</idno><idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6727172</idno><idno type="RBID">PMC:6727172</idno><idno type="doi">10.1107/S2053229619010714</idno><date when="2019">2019</date><idno type="wicri:Area/Pmc/Corpus">000975</idno><idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">000975</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">Deciphering the hydrogen-bonding scheme in the crystal structure of triphenylmethanol: a tribute to George Ferguson and co-workers</title><author><name sortKey="Rodriguez Tzompantzi, Tomasa" sort="Rodriguez Tzompantzi, Tomasa" uniqKey="Rodriguez Tzompantzi T" first="Tomasa" last="Rodríguez Tzompantzi">Tomasa Rodríguez Tzompantzi</name><affiliation><nlm:aff id="a">Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author><author><name sortKey="Amaro Hernandez, Aldo Guillermo" sort="Amaro Hernandez, Aldo Guillermo" uniqKey="Amaro Hernandez A" first="Aldo Guillermo" last="Amaro Hernández">Aldo Guillermo Amaro Hernández</name><affiliation><nlm:aff id="a">Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author><author><name sortKey="Meza Le N, Rosa Luisa" sort="Meza Le N, Rosa Luisa" uniqKey="Meza Le N R" first="Rosa Luisa" last="Meza-Le N">Rosa Luisa Meza-Le N</name><affiliation><nlm:aff id="a">Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author><author><name sortKey="Bernes, Sylvain" sort="Bernes, Sylvain" uniqKey="Bernes S" first="Sylvain" last="Bernès">Sylvain Bernès</name><affiliation><nlm:aff id="b">Instituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></nlm:aff></affiliation></author></analytic><series><title level="j">Acta Crystallographica. Section C, Structural Chemistry</title><idno type="eISSN">2053-2296</idno><imprint><date when="2019">2019</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en"><p>The disordered crystal structure of triphenylmethanol features tetrahedral chiral clusters formed through weak hydrogen bonds, leading to the formation of three-dimensional supramolecular motifs having left or right handedness.</p></div></front><back><div1 type="bibliography"><listBibl><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct></listBibl></div1></back></TEI><pmc article-type="research-article"><pmc-dir>properties open_access</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-ta">Acta Crystallogr C Struct Chem</journal-id><journal-id journal-id-type="iso-abbrev">Acta Crystallogr C Struct Chem</journal-id><journal-id journal-id-type="publisher-id">Acta Cryst. C</journal-id><journal-title-group><journal-title>Acta Crystallographica. Section C, Structural Chemistry</journal-title></journal-title-group><issn pub-type="epub">2053-2296</issn><publisher><publisher-name>International Union of Crystallography</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="pmid">31484815</article-id><article-id pub-id-type="pmc">6727172</article-id><article-id pub-id-type="publisher-id">cu3146</article-id><article-id pub-id-type="doi">10.1107/S2053229619010714</article-id><article-id pub-id-type="coden">ACSCGG</article-id><article-id pub-id-type="pii">S2053229619010714</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Papers</subject></subj-group></article-categories><title-group><article-title>Deciphering the hydrogen-bonding scheme in the crystal structure of triphenylmethanol: a tribute to George Ferguson and co-workers</article-title><alt-title><italic>The hydrogen-bonding scheme in triphenylmethanol</italic></alt-title></title-group><contrib-group><contrib contrib-type="author"><name><surname>Rodríguez Tzompantzi</surname><given-names>Tomasa</given-names></name><xref ref-type="aff" rid="a">a</xref></contrib><contrib contrib-type="author"><name><surname>Amaro Hernández</surname><given-names>Aldo Guillermo</given-names></name><xref ref-type="aff" rid="a">a</xref></contrib><contrib contrib-type="author"><name><surname>Meza-León</surname><given-names>Rosa Luisa</given-names></name><xref ref-type="aff" rid="a">a</xref></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid" authenticated="true">https://orcid.org/0000-0001-9209-7580</contrib-id><name><surname>Bernès</surname><given-names>Sylvain</given-names></name><xref ref-type="aff" rid="b">b</xref><xref ref-type="corresp" rid="cor">*</xref></contrib><aff id="a"><label>a</label>Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></aff><aff id="b"><label>b</label>Instituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue.,<country>Mexico</country></aff></contrib-group><author-notes><corresp id="cor">Correspondence e-mail: <email>sylvain_bernes@hotmail.com</email></corresp></author-notes><pub-date pub-type="collection"><day>01</day><month>9</month><year>2019</year></pub-date><pub-date pub-type="epub"><day>14</day><month>8</month><year>2019</year></pub-date><pub-date pub-type="pmc-release"><day>14</day><month>8</month><year>2019</year></pub-date><pmc-comment> PMC Release delay is 0 months and 0 days and was based on the
<volume>75</volume><issue>Pt 9</issue><issue-id pub-id-type="publisher-id">c190900</issue-id><fpage>1266</fpage><lpage>1273</lpage><history><date date-type="received"><day>23</day><month>4</month><year>2019</year></date><date date-type="accepted"><day>30</day><month>7</month><year>2019</year></date></history><permissions><copyright-statement>© Rodríguez Tzompantzi et al. 2019</copyright-statement><copyright-year>2019</copyright-year><license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by/4.0/"><license-p>This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original authors and source are cited.</license-p><ali:license_ref>http://creativecommons.org/licenses/by/4.0/</ali:license_ref></license></permissions><self-uri xlink:href="https://doi.org/10.1107/S2053229619010714">A full version of this article is available from Crystallography Journals Online.</self-uri><abstract abstract-type="toc"><p>The disordered crystal structure of triphenylmethanol features tetrahedral chiral clusters formed through weak hydrogen bonds, leading to the formation of three-dimensional supramolecular motifs having left or right handedness.</p></abstract><abstract><p>The crystal structure of triphenylmethanol, C<sub>19</sub>H<sub>16</sub>O, has been redetermined using data collected at 295 and 153 K, and is compared to the model published by Ferguson <italic>et al.</italic> over 25 years ago [Ferguson <italic>et al.</italic> (1992<xref ref-type="bibr" rid="bb13"> ▸</xref>). <italic>Acta Cryst</italic>. C<bold>48</bold>, 1272–1275] and that published by Serrano-González <italic>et al.</italic>, using neutron and X-ray diffraction data [Serrano-González <italic>et al.</italic> (1999<xref ref-type="bibr" rid="bb29"> ▸</xref>). <italic>J. Phys. Chem. B</italic>, <bold>103</bold>, 6215–6223]. As predicted by these authors, the hydroxy groups are involved in weak intermolecular hydrogen bonds in the crystal, forming tetrahedral tetramers based on the two independent molecules in the asymmetric unit, one of which is placed on the threefold symmetry axis of the <italic>R</italic><inline-formula><inline-graphic xlink:href="c-75-01266-efi1.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula> space group. However, the reliable determination of the hydroxy H-atom positions is difficult to achieve, for two reasons. Firstly, a positional disorder affects the full asymmetric unit, which is split over two sets of positions, with occupancy factors of <italic>ca</italic> 0.74 and 0.26. Secondly, all hydroxy H atoms are further disordered, either by symmetry, or through a positional disorder in the case of parts placed in general positions. We show that the correct description of the hydrogen-bonding scheme is possible only if diffraction data are collected at low temperature. The prochiral character of the hydrogen-bonded tetrameric supramolecular clusters leads to enantiomorphic three-dimensional graphs in each tetramer. The crystal is thus a racemic mixture of <sup>sup</sup><italic>S</italic> and <sup>sup</sup><italic>R</italic> motifs, consistent with the centrosymmetric nature of the <italic>R</italic><inline-formula><inline-graphic xlink:href="c-75-01266-efi1.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula> space group.</p></abstract><kwd-group><kwd>alcohol</kwd><kwd>hydrogen bond</kwd><kwd>disorder</kwd><kwd>topological chirality</kwd><kwd>crystal structure</kwd><kwd>triphenylmethanol</kwd></kwd-group><funding-group><award-group><funding-source>Consejo Nacional de Ciencia y Tecnología</funding-source><award-id>268178</award-id><award-id>304678</award-id></award-group><award-group><funding-source>VIEP-BUAP</funding-source><award-id>100317000-VIEP2018</award-id></award-group><funding-statement>This work was funded by <funding-source>Consejo Nacional de Ciencia y Tecnología</funding-source> grants <award-id>268178</award-id> and <award-id>304678</award-id>. <funding-source>VIEP-BUAP</funding-source> grant <award-id>100317000-VIEP2018</award-id>. </funding-statement></funding-group><counts><page-count count="8"></page-count></counts></article-meta></front><body><sec sec-type="introduction" id="sec1"><title>Introduction </title><p>The hydroxy group is known as one of the most efficient nodes for the formation of hydrogen bonds, as a consequence of the polarization of the O—H bond, and also because it can behave both as donor and acceptor for building intra- or intermolecular bonds. In this context, the emblematic donor–acceptor molecule is water, and many compounds have been crystallized as hydrates, in which the lattice water molecules contribute to a significant part of the crystal free energy (Batsanov, 2018<xref ref-type="bibr" rid="bb6"> ▸</xref>); currently, almost 13% of the structures deposited in the Cambridge Structural Database are hydrates (CSD, Version 5.40, updated February 2019; Groom <italic>et al.</italic>, 2016<xref ref-type="bibr" rid="bb17"> ▸</xref>). The situation is a bit less favourable in the case of alcohols (<italic>R</italic>O—H), especially for tertiary alcohols having the hydroxy group surrounded by bulky hydrocarbon groups. For example, three hydrates for <italic>tert</italic>-butanol, (CH<sub>3</sub>)<sub>3</sub>COH, have been successfully characterized [namely the dihydrate and heptahydrate (Mootz & Stäben, 1993<xref ref-type="bibr" rid="bb23"> ▸</xref>), and the decahydrate (Dobrzycki, 2018<xref ref-type="bibr" rid="bb10"> ▸</xref>)], while tri-<italic>tert</italic>-butylmethanol, [(CH<sub>3</sub>)<sub>3</sub>C]<sub>3</sub>COH, has probably never been crystallized, although it has been studied in the solid state (Malarski, 1974<xref ref-type="bibr" rid="bb22"> ▸</xref>). Although this molecule is stable, it is not able to form stabilizing intermolecular O—H⋯O hydrogen bonds, because of the steric hindrance of the three <italic>tert</italic>-butyl groups surrounding the OH donor group (Majerz & Natkaniec, 2006<xref ref-type="bibr" rid="bb21"> ▸</xref>).<chem-struct id="scheme1"><graphic xlink:href="c-75-01266-scheme1.jpg" position="float" orientation="portrait"></graphic></chem-struct></p><p>The case of triphenylmethanol, (C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>COH, should be intermediate between <italic>tert</italic>-butanol and tri-<italic>tert</italic>-butylmethanol, since it can be used as a clathrate host for methanol (Weber <italic>et al.</italic>, 1989<xref ref-type="bibr" rid="bb37"> ▸</xref>), and may be hydrogen bonded to a water molecule (Batisai <italic>et al.</italic>, 2016<xref ref-type="bibr" rid="bb5"> ▸</xref>), dimethyl sulfoxide, dimethylformamide (Eckardt <italic>et al.</italic>, 1999<xref ref-type="bibr" rid="bb12"> ▸</xref>) or Ph<sub>3</sub>P=O (Steiner, 2000<xref ref-type="bibr" rid="bb33"> ▸</xref>). Indeed, unsolvated triphenylmethanol can be easily crystallized from benzene or ethanol, affording large well-shaped clear colourless single crystals. However, these crystals are always weakly diffracting samples, as a consequence of a severe structural disorder (<italic>vide infra</italic>). The resulting ratio of observed to measured reflections is then quite low, which, in turn, makes the refinement very difficult. First attempts to refine a reasonable model failed (Weber <italic>et al.</italic>, 1989<xref ref-type="bibr" rid="bb37"> ▸</xref>), and it was only in 1992 that the crystal structure was published (Ferguson <italic>et al.</italic>, 1992<xref ref-type="bibr" rid="bb13"> ▸</xref>), based on room-temperature intensities measured on a CAD-4 diffractometer, with Mo <italic>K</italic>α radiation. 2467 unique reflections were used, of which 41% were observed [<italic>I</italic> > 2.5σ(<italic>I</italic>)], and the structure was refined with a structural motif described as a ‘hydrogen-bonded pyramidal tetramer which is disordered (71/29) about two interpenetrating sites’. The refinement was of limited accuracy and converged to <italic>R</italic> = 0.083 and <italic>wR</italic> = 0.068 with rigid idealized phenyl rings for all molecules, and isotropic atoms in the minor-disordered part of the asymmetric unit (253 variable parameters).</p><p>Although the structure reported by Ferguson <italic>et al.</italic> was incomplete, since hydroxy H atoms could not be located, the <italic>savoir-faire</italic> used by this team is quite impressive. They were able to solve and refine this challenging disordered structure, while others probably gave up by arguing that crystals were badly twinned. Above all, they did not attempt to over-interpret their data, and were aware that hydroxy H atoms were very imprecisely determined in their X-ray diffraction experiment. However, they indirectly recognized and described the presence of a weak hydrogen-bonding scheme, reflected in intermolecular O⋯O contacts.</p><p>In 1999, Serrano-González <italic>et al.</italic> (1999<xref ref-type="bibr" rid="bb29"> ▸</xref>) published a more elaborate article, focussed on the characterization of the hydrogen-bonding arrangement in triphenylmethanol, using neutron (<italic>T</italic> = 100 K) and X-ray diffraction data (<italic>T</italic> = 113 and 293 K), as well as solid-state <sup>13</sup>C NMR spectroscopy. A reliable structure based on neutron diffraction data was obtained, showing that each independent OH group has the H atom disordered over three sites. This model was then a suitable starting point for the refinement of X-ray structures, both at 113 and 293 K. Unfortunately, the final atomic coordinates were never deposited in the CSD, and there is no CIF available as supporting information. Fractional coordinates are tabulated, however, for X-ray refinements, H atoms are missing. Moreover, even using the favourable neutron scattering length for the protium nucleus, it was not possible to complete the structure. As stated in this article ‘The hydroxy hydrogens of the minor tetramer could not be located from the difference Fourier map, and these hydrogen atoms were inserted in calculated positions based on those determined […] for the major tetramer’.</p><p>We have now completed these works, using X-ray data collected at room temperature and low temperature with the Ag <italic>K</italic>α radiation, revealing the accurate localization of the hydroxy H atoms in the disordered structure. A comprehensive insight into the hydrogen-bonding scheme that held together the tetrameric clusters is now afforded.</p></sec><sec sec-type="methods" id="sec2"><title>Experimental </title><sec id="sec2.1"><title>Synthesis and crystallization </title><p>We obtained triphenylmethanol as a by-product during the oxidative hydrolysis of the diacetylated compound (<bold>1</bold>), following a method proposed by Barton <italic>et al.</italic> (1972<xref ref-type="bibr" rid="bb4"> ▸</xref>) (Fig. 1<xref ref-type="fig" rid="fig1"> ▸</xref>). Compound (<bold>1</bold>) (0.100 g, 0.318 mmol) and triphenylcarbenium tetrafluoroborate (0.099 g, 0.380 mmol) were mixed in dry CH<sub>2</sub>Cl<sub>2</sub> (20 ml) and stirred for 15 min at room temperature. A saturated solution of NaHCO<sub>3</sub> was then added (10 ml), the organic phase dried over Na<sub>2</sub>SO<sub>4</sub> and the crude product chromatographed (silica gel, hexane–ethyl acetate, 90:10 <italic>v</italic>/<italic>v</italic>). The expected hydroxy aldehyde (<bold>2</bold>) was not observed, and the dimer (<bold>3</bold>) was isolated instead, mixed with triphenylmethane and triphenylmethanol. It was not possible to separate (<bold>3</bold>) and triphenylmethanol by chromatography, whereby the mixture was purified by crystallization in hexane–ethyl acetate (95:5 <italic>v</italic>/<italic>v</italic>), affording large single crystals of triphenylmethanol [yield 30 mg; m.p. 431–433 K, literature 434–435 K (Zeiss & Tsutsui, 1953<xref ref-type="bibr" rid="bb40"> ▸</xref>)]. <sup>1</sup>H NMR (CDCl<sub>3</sub>/TMS, 300 MHz): δ 2.8 (<italic>s</italic>, 1H, OH), 7.30 (<italic>s</italic>, 15H, Ph). <sup>13</sup>C NMR (CDCl<sub>3</sub>/TMS, 75 MHz): δ 99.8 (C—OH), 127.2, 127.9, 146.8 (Ph).</p></sec><sec id="sec2.2"><title>Refinements </title><p>Crystal data, data collection and structure refinement details are summarized in Table 1<xref ref-type="table" rid="table1"> ▸</xref> for the two different crystals obtained from a single crystallization batch, but diffracted at different temperatures, <italic>i.e.</italic> 153 and 295 K. The disorder in the asymmetric unit was solved using the low-temperature data set, and all phenyl rings were restrained to be flat, with standard deviations of 0.1 Å<sup>3</sup>. Additionally, the phenyl rings in the minor part (molecules <italic>C</italic> and <italic>D</italic>) were restrained to have 1,3 distances similar to those in the corresponding rings of the disordered counterpart (molecules <italic>A</italic> and <italic>B</italic>), within standard deviations of 0.02 Å. H atoms in the phenyl rings were placed in idealized positions and refined as riding to their carrier C atoms, with <italic>U</italic><sub>iso</sub>(H) = 1.2<italic>U</italic><sub>eq</sub>(C). Hydroxy H atoms were found in a difference map (Fig. 2<xref ref-type="fig" rid="fig2"> ▸</xref>, left) and refined with <italic>U</italic><sub>iso</sub>(H) = 1.5<italic>U</italic><sub>eq</sub>(O). Atoms H1<italic>A</italic> and H1<italic>C</italic> are disordered by symmetry, and their site occupancies were fixed as one-third of the occupancy of the part to which they belong. The hydroxy H atoms for molecules in general positions are disordered over sites H1<italic>BA</italic>, H1<italic>BB</italic> and H1<italic>BC</italic> for molecule <italic>B</italic>, and H1<italic>DA</italic>, H1<italic>DB</italic> and H1<italic>DC</italic> for molecule <italic>D</italic>, and the occupancy for each site was also fixed as one-third of the occupancy of the part to which it belongs. The geometry of the C—O—H groups was first restrained to a sensible target, by restraining distances to O—H = 0.85 (1) Å and C⋯H = 1.93 (2) Å in molecules <italic>A</italic> and <italic>C</italic>; for molecules <italic>B</italic> and <italic>D</italic>, the applied restraints were O—H = <italic>d</italic>, H⋯H = (8/3)<sup>1/2</sup> × <italic>d</italic> and C⋯H = 2.27 × <italic>d</italic>, where <italic>d</italic> is a common free variable. Standard deviations for these restraints were 0.02, 0.03 and 0.03 Å, respectively. After convergence, the positions of all hydroxy H atoms were fixed, and these atoms were refined as riding on their carrier O atoms. The final model for the complete structure at 153 K was refined against data collected at 295 K, with an extra restraint: in the minor-disordered part (molecules <italic>C</italic> and <italic>D</italic>), rigid-bond restraints were applied with standard deviations of 0.004 Å for the 1,2 and 1,3 distances (Thorn <italic>et al.</italic>, 2012<xref ref-type="bibr" rid="bb35"> ▸</xref>; Sheldrick, 2015<italic>b</italic><xref ref-type="bibr" rid="bb32"> ▸</xref>).</p></sec></sec><sec sec-type="discussion|interpretation" id="sec3"><title>Results and discussion </title><p>The asymmetric unit of the trigonal cell includes two disordered parts with site-occupancy factors converging at 153 K towards 0.7436 (17) (molecules <italic>A</italic> and <italic>B</italic> hereafter) and 0.2564 (17) (molecules <italic>C</italic> and <italic>D</italic> hereafter), close to the occupancies reported by Ferguson <italic>et al.</italic> of 0.71 and 0.29. Each part contains two independent molecules, one of which has the σ C—O bond lying on the threefold axis in the space group <italic>R</italic><inline-formula><inline-graphic xlink:href="c-75-01266-efi1.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>, while the other is located in a general position. The arrangement of these four disordered molecules generates overlapped phenyl rings in the asymmetric unit, making the refinement of displacement parameters a tedious task (see §2.2<xref ref-type="sec" rid="sec2.2"></xref>). However, the molecular structure based on data collected at 153 K can be considered as satisfactory, although the refinement was carried out with restrained geometry for the phenyl rings. The refinement based on data collected at 295 K is not as easy, since the scattering power of the crystal decreases dramatically: the fraction of observed data [<italic>I</italic>/σ(<italic>I</italic>) > 2] drops from 50% at 153 K to 36% at 295 K. However, the structure is essentially unmodified, and occupancies for the disordered parts refined to 0.761 (3) and 0.239 (3). At both temperatures, all non-H atoms could be refined anisotropically (see Fig. 2<xref ref-type="fig" rid="fig2"> ▸</xref>, right), after which phenyl H atoms were placed in idealized positions.</p><p>The localization of the hydroxy H atoms was far more complex. A difference map using room-temperature data is useless, in contrast to the map computed with data collected at low temperature. At 153 K, most of the positive residuals are found close to the O atoms (Fig. 2<xref ref-type="fig" rid="fig2"> ▸</xref>, left), allowing the determination of sensible coordinates for H atoms disordered by symmetry (H1<italic>A</italic> and H1<italic>C</italic> for molecules <italic>A</italic> and <italic>C</italic> in special positions). At this point, the highest residuals are found close to O1<italic>B</italic>, forming a tetrahedral geometry with O1<italic>B</italic>; although molecule <italic>B</italic> is located in a general position, the O—H group emulates the disorder imposed by symmetry in molecule <italic>A</italic> (see top inset in Fig. 3<xref ref-type="fig" rid="fig3"> ▸</xref>). The same situation is repeated for molecule <italic>D</italic>, with much smaller residuals because this molecule belongs to the minor part of the disordered asymmetric unit. Ultimately, all the molecules in the crystal have their hydroxy H atoms disordered over three sites, and once the asymmetric unit is expanded to tetramers, eight independent molecules are clustered in such a way that the cavity delimited by eight O atoms is filled with 24 sites for disordered hydroxy H atoms (Fig. 2<xref ref-type="fig" rid="fig2"> ▸</xref>, right). Each C—O—H group can also be seen as a rigid group rotating about its C—O axis, producing for the H atom an electron density smeared out over a ring; nevertheless, the free rotation should be hindered through the formation of weak hydrogen bonds (Schröder <italic>et al.</italic>, 2004<xref ref-type="bibr" rid="bb27"> ▸</xref>). Such a description would be consistent with <sup>2</sup>H NMR spectroscopy experiments carried out on Ph<sub>3</sub>COD, showing that each hydroxy group is dynamic by rotation about the C—OD bond, on the 10<sup>−3</sup> to 10<sup>−8</sup> s time scale (Aliev <italic>et al.</italic>, 1998<xref ref-type="bibr" rid="bb1"> ▸</xref>).</p><p>All OH groups behave as donor groups for intermolecular O—H⋯O hydrogen bonds. For the main part <italic>A</italic>/<italic>B</italic>, with occupancy = 0.74, three <italic>B</italic> molecules placed close to the threefold axis are connected to form an <inline-formula><inline-graphic xlink:href="c-75-01266-efi4.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(6) ring, corresponding to a first-level graph with H1<italic>BB</italic> as donor (Table 2<xref ref-type="table" rid="table2"> ▸</xref>, entry 3). This motif is repeated with H1<italic>BC</italic> (Table 2<xref ref-type="table" rid="table2"> ▸</xref>, entry 4), however, if the crystal orientation is preserved, this ring motif is enantiomorphic with the previous one. Finally, the third disordered site for the hydroxy H atom, H1<italic>BA</italic>, is engaged in a second-level graph with O1<italic>A</italic> as acceptor (Table 2<xref ref-type="table" rid="table2"> ▸</xref>, entry 2), giving a ring motif <inline-formula><inline-graphic xlink:href="c-75-01266-efi5.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(6). Site O1<italic>A</italic> also serves as a donor, forming three symmetry-equivalent O1<italic>A</italic>—H1<italic>A</italic>⋯O1<italic>B</italic> hydrogen bonds (Table 2<xref ref-type="table" rid="table2"> ▸</xref>, entry 1), and is involved in the largest rings, <inline-formula><inline-graphic xlink:href="c-75-01266-efi6.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(8). All rings are depicted in Fig. 3<xref ref-type="fig" rid="fig3"> ▸</xref>, along with schematic representations of the corresponding graphs and their pathways [<italic>i.e.</italic> the <italic>constructor graphs</italic> and the <italic>qualitative descriptors</italic>, in the terminology coined by Motherwell <italic>et al.</italic> (1999<xref ref-type="bibr" rid="bb24"> ▸</xref>)].</p><p>The tetramer based on <italic>A</italic> and <italic>B</italic> molecules includes 12 hydrogen bonds. Each disordered hydroxy H atom is engaged in a single hydrogen bond, and each O atom serves three times as acceptor (Fig. 4<xref ref-type="fig" rid="fig4"> ▸</xref>, left). The hydrogen-bonded supramolecular cluster formed in the tetramer is associated with a topological graph embedded in 3-space, <italic>i.e.</italic><italic>G</italic>(4,6) = [<inline-formula><inline-graphic xlink:href="c-75-01266-efi4.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(6)<inline-formula><inline-graphic xlink:href="c-75-01266-efi6.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(8)<inline-formula><inline-graphic xlink:href="c-75-01266-efi5.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(6)], for which the faces are the <italic>R</italic>(<italic>n</italic>) rings described in Fig. 3<xref ref-type="fig" rid="fig3"> ▸</xref>. In the parlance of graph theory, the finite directed graph <italic>G</italic>(4,6) based on the ‘<italic>pyramidal tetramer</italic>’ mentioned by Ferguson <italic>et al.</italic> is regular, complete and intrinsically chiral (Flapan, 1995<xref ref-type="bibr" rid="bb15"> ▸</xref>). The four nodes for <italic>G</italic>(4,6) are provided by four molecules (or four hydroxy O atoms for simplicity) and the six arrows are oriented O—H⋯O hydrogen bonds, the tail of the arrow being the donor OH group and the head being the acceptor O atom. It is noteworthy that for each right-handed <italic>R</italic>(<italic>n</italic>) ring, there is one related left-handed ring, as illustrated in Fig. 3<xref ref-type="fig" rid="fig3"> ▸</xref>. For example, in the first-level <inline-formula><inline-graphic xlink:href="c-75-01266-efi4.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(6) subgraph embedded in the 2-space, arrows rotate clockwise around the crystallographic threefold axis for the ring including arrows O1<italic>B</italic>—H1<italic>BB</italic>⋯O1<italic>B</italic> (<italic>Rectus</italic> face for topological graph <italic>G</italic>), and anticlockwise for the ring including arrows O1<italic>B</italic>—H1<italic>BC</italic>⋯O1<italic>B</italic> (<italic>Sinister</italic> face for topological graph <italic>G</italic>).</p><p>A topologically isomorphous graph <italic>G</italic>′(4,6) can be built with the minor part of the asymmetric unit, including hydrogen bonds similar to those described for the main tetramer, although the relative positions of the 12 H-atom sites is modified through a small rotation around the C1<italic>C</italic>—O1<italic>C</italic> axis (Fig. 4<xref ref-type="fig" rid="fig4"> ▸</xref>, right). Therefore, the mixture of eight molecules built on the asymmetric unit, as represented in Fig. 2<xref ref-type="fig" rid="fig2"> ▸</xref>, affords a racemic mixture of supramolecular enantiomorphic tetramers <sup>sup</sup><italic>R</italic> and <sup>sup</sup><italic>S</italic> built on 24 hydrogen bonds. Obviously, the molecules themselves are achiral, but the supramolecular chirality results from the asymmetric configuration of the hydrogen bonds (Sasaki <italic>et al.</italic>, 2014<xref ref-type="bibr" rid="bb26"> ▸</xref>). Neither the unit cell nor the crystal are chiral objects, since the molecule crystallizes in a centrosymmetric space group, <italic>R</italic><inline-formula><inline-graphic xlink:href="c-75-01266-efi1.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>.</p><p>The set of 24 hydrogen bonds depicted in Fig. 4<xref ref-type="fig" rid="fig4"> ▸</xref> comprises only weak hydrogen bonds, with H⋯O separations in the range 2.21–2.38 Å and O—H⋯O angles far from linearity, in the range 121.4–138.2°, at 153 K. The refinement using room-temperature data indicates that the supramolecular chiral clusters are retained, although hydrogen bonds are slightly weakened by <italic>ca</italic> 0.06 Å for H⋯O separations (compare Tables 2<xref ref-type="table" rid="table2"> ▸</xref> and 3<xref ref-type="table" rid="table3"> ▸</xref>). These geometric parameters were compared with those found in other supramolecular networks formed in the crystalline state by tertiary alcohols, using the methodology developed at the CCDC (Wood <italic>et al.</italic>, 2009<xref ref-type="bibr" rid="bb39"> ▸</xref>). Parameters for intermolecular O—H⋯O contacts in tertiary alcohols were retrieved from the current release of the CSD, omitting disordered, polymeric and ionic structures. Hydroxy H-atom positions were normalized within <italic>ConQuest</italic> to O—H = 0.993 Å, in order to avoid systematic errors in contact distances (Bruno <italic>et al.</italic>, 2002<xref ref-type="bibr" rid="bb9"> ▸</xref>). The search was limited to organic compounds not flagged with errors, and reported with <italic>R</italic><sub>1</sub> < 0.075, affording 1215 hits, corresponding to 1812 raw data (<italic>d</italic>, θ), where <italic>d</italic> is the H⋯O distance and θ is the O—H⋯O angle. Only contacts with <italic>d</italic> shorter than the van der Waals (vdW) distance were retained [<italic>r</italic><sub>vdW</sub>(H) + <italic>r</italic><sub>vdW</sub>(O) = 2.72 Å; Bondi, 1964<xref ref-type="bibr" rid="bb7"> ▸</xref>]. Data were converted into spherical polar coordinates (<italic>x</italic>, <italic>y</italic>), where <italic>x</italic> = (<italic>d</italic>/2.72)<sup>3</sup> and <italic>y</italic> = 1 − cos (180 − θ), assuming that <italic>d</italic> and θ are expressed in Å and °, respectively (Lommerse <italic>et al.</italic>, 1996<xref ref-type="bibr" rid="bb19"> ▸</xref>). A two-dimensional (2D) frequency binning histogram representation of the (<italic>x</italic>, <italic>y</italic>) distribution shows a sharp peak about (<italic>d</italic>, θ) = (1.82 Å, 180°), as expected for O—H⋯O hydrogen bonds (Fig. 5<xref ref-type="fig" rid="fig5"> ▸</xref>). A significant frequency is still observed about (<italic>d</italic>, θ) = (1.87 Å, 145°). Outside these well-defined territories, the observed frequency collapses.</p><p>Interestingly, the title compound displays O—H⋯O contacts on the borderline between truly hydrogen-bonded alcohols and the near-zero frequency area (see green patch on the ground level in Fig. 5<xref ref-type="fig" rid="fig5"> ▸</xref>). However, although of very limited strength, hydrogen bonds in the tetramers depicted in Fig. 3<xref ref-type="fig" rid="fig3"> ▸</xref> are genuinely present, as reflected in the Hirshfeld surface for any pair of molecules involved in a tetrameric supramolecular cluster (Fig. 5<xref ref-type="fig" rid="fig5"> ▸</xref>, inset). In other words, triphenylmethanol could represent the boundary between hydrogen-bonded and non-hydrogen-bonded tertiary alcohols. This also opens the possibility that a phase transition occurs for triphenylmethanol somewhere between <italic>T</italic> = 293 and 433 K (melting point), if thermal energy <italic>kT</italic> is able to dismantle the network of weak hydrogen bonds.</p><p>In order to evaluate the stability of the noncovalent bonds in this crystal, George Ferguson and co-workers came across a more chemical strategy, by determining the crystal structures of molecules isoelectronic with triphenylmethanol (Glidewell & Ferguson, 1994<xref ref-type="bibr" rid="bb16"> ▸</xref>). Their hypothesis was that ‘with only modest changes in the steric demands at the unique central C atom, while keeping the number of hydrogen-bond donors and acceptors unchanged, the patterns of hydrogen bonding can be altered drastically’. Indeed, diphenyl(pyridin-4-yl)methanol has a simple achiral supramolecular structure based on <italic>C</italic>(7) chains. For triphenylmethanamine, two polymorphic forms have been described: the orthorhombic phase does not form hydrogen bonds at all (Glidewell & Ferguson, 1994<xref ref-type="bibr" rid="bb16"> ▸</xref>), while the triclinic phase features dimers through the formation of N—H⋯N hydrogen bonds, due to the statistical disordering of the amino H atoms (Khrustalev <italic>et al.</italic>, 2009<xref ref-type="bibr" rid="bb18"> ▸</xref>; Schulz <italic>et al.</italic>, 2013<xref ref-type="bibr" rid="bb28"> ▸</xref>). The NH<sub>2</sub> group then displays a geometry reminiscent of that of the OH groups in triphenylmethanol. However, no chiral supramolecular clusters are formed with the amine, and the asymmetric unit includes a single nondisordered molecule. A rhombohedral polymorph for this amine has also been deposited recently; unfortunately, after inspection of this structure, it turns out that the formula is wrong: the diffracted crystal was almost certainly triphenylmethanol (Bagchi <italic>et al.</italic>, 2014<xref ref-type="bibr" rid="bb3"> ▸</xref>; <italic>R</italic><inline-formula><inline-graphic xlink:href="c-75-01266-efi1.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula> space group, <italic>T</italic> = 298 K, <italic>R</italic><sub>1</sub> = 10%). In the opposite direction, strong O—H⋯O hydrogen bonds can be restored in sterically hindered tertiary alcohols by just adding a methylene group: in the crystal structure of triphenylethanol, Ph<sub>3</sub>CCH<sub>2</sub>OH (nondisordered <italic>P</italic>2<sub>1</sub>/<italic>c</italic> crystal, <italic>Z</italic>′ = 2; Ferguson <italic>et al.</italic>, 1994<xref ref-type="bibr" rid="bb14"> ▸</xref>), molecules aggregate into discrete achiral <inline-formula><inline-graphic xlink:href="c-75-01266-efi13.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>(8) rings. In comparison with triphenylmethanol, the prochiral character of the supramolecular structure is lost, and the compound lies within a sharp peak of ‘normal’ crystal structures in a (<italic>x</italic>, <italic>y</italic>) distribution similar to that depicted for tertiary alcohols in Fig. 5<xref ref-type="fig" rid="fig5"> ▸</xref>.</p></sec><sec sec-type="conclusions" id="sec4"><title>Concluding remarks </title><p>Triphenylmethanol is a small simple molecule with a structure unexpectedly difficult to refine compared, for example, to that of triphenylsilanol (Bowes <italic>et al.</italic>, 2002<xref ref-type="bibr" rid="bb8"> ▸</xref>). It is worthwhile to consider the evolution of X-ray diffractometry over the last 25 years, using triphenylmethanol as a benchmark (Table 4<xref ref-type="table" rid="table4"> ▸</xref>; data at room temperature were retained in order to avoid biases). The time taken for data collection is almost identical in the three cases, <italic>ca</italic> 20–30 h, and there is little doubt that the diffracted samples were of similar quality. Over time, a steady progress is noted. Development of new technologies for the detection of scattered X-ray photons seems to be the key point, in such a way that location of tiny fractions of electrons in the crystal space is now routinely affordable, outside the multipole density formalism. There is indeed a consensus that the hybrid pixel detectors with CdTe or GaAs sensors represent the ultimate state-of-art technology in this field, since they detect all scattered X-rays, with 100% efficiency and without any noise (Allé <italic>et al.</italic>, 2016<xref ref-type="bibr" rid="bb2"> ▸</xref>). For the herein presented study, a Pilatus detector was used, with a 1000 µm-thick silicon sensor, which has a quantum efficiency of 50% for 22.2 keV photons (Ag <italic>K</italic>α radiation).</p></sec><sec sec-type="supplementary-material"><title>Supplementary Material</title><supplementary-material content-type="local-data"><p>Crystal structure: contains datablock(s) 153K_data, 295K_data, global. DOI: <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1107/S2053229619010714/cu3146sup1.cif">10.1107/S2053229619010714/cu3146sup1.cif</ext-link></p><media mimetype="chemical" mime-subtype="x-cif" xlink:href="c-75-01266-sup1.cif" orientation="portrait" id="d35e128" position="anchor"></media></supplementary-material><supplementary-material content-type="local-data"><p>Structure factors: contains datablock(s) 153K_data. DOI: <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1107/S2053229619010714/cu3146153K_datasup2.hkl">10.1107/S2053229619010714/cu3146153K_datasup2.hkl</ext-link></p><media mimetype="text" mime-subtype="plain" xlink:href="c-75-01266-153K_datasup2.hkl" orientation="portrait" id="d35e135" position="anchor"></media></supplementary-material><supplementary-material content-type="local-data"><p>Structure factors: contains datablock(s) 295K_data. DOI: <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1107/S2053229619010714/cu3146295K_datasup3.hkl">10.1107/S2053229619010714/cu3146295K_datasup3.hkl</ext-link></p><media mimetype="text" mime-subtype="plain" xlink:href="c-75-01266-295K_datasup3.hkl" orientation="portrait" id="d35e142" position="anchor"></media></supplementary-material><supplementary-material content-type="local-data"><media xlink:href="c-75-01266-153K_datasup4.cml"><caption><p>Click here for additional data file.</p></caption></media><p>Supporting information file. DOI: <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1107/S2053229619010714/cu3146153K_datasup4.cml">10.1107/S2053229619010714/cu3146153K_datasup4.cml</ext-link></p></supplementary-material><supplementary-material content-type="local-data"><p>CCDC references: <ext-link ext-link-type="uri" xlink:href="https://scripts.iucr.org/cgi-bin/cr.cgi?rm=csd&csdid=1944593">1944593</ext-link>, <ext-link ext-link-type="uri" xlink:href="https://scripts.iucr.org/cgi-bin/cr.cgi?rm=csd&csdid=1944592">1944592</ext-link></p></supplementary-material></sec></body><back><ack><p>The submitting author thanks an anonymous referee for his guidance regarding the accurate interpretation of the difference map depicted in Fig. 2<xref ref-type="fig" rid="fig2"> ▸</xref>.</p></ack><ref-list><title>References</title><ref id="bb1"><mixed-citation publication-type="other">Aliev, A. E., MacLean, E. J., Harris, K. D. M., Kariuki, B. M. & Glidewell, C. (1998). <italic>J. Phys. Chem. B</italic>, <bold>102</bold>, 2165–2175.</mixed-citation></ref><ref id="bb2"><mixed-citation publication-type="other">Allé, P., Wenger, E., Dahaoui, S., Schaniel, D. & Lecomte, C. (2016). <italic>Phys. Scr.</italic><bold>91</bold>, 063001.</mixed-citation></ref><ref id="bb3"><mixed-citation publication-type="other">Bagchi, V., Paraskevopoulou, P., Das, P., Chi, L., Wang, Q., Choudhury, A., Mathieson, J. S., Cronin, L., Pardue, D. B., Cundari, T. R., Mitrikas, G., Sanakis, Y. & Stavropoulos, P. (2014). <italic>J. Am. Chem. Soc.</italic><bold>136</bold>, 11362–11381.</mixed-citation></ref><ref id="bb4"><mixed-citation publication-type="other">Barton, D. H. R., Magnus, P. D., Smith, G., Streckert, G. & Zurr, D. (1972). <italic>J. Chem. Soc. Perkin Trans. 1</italic>, pp. 542–552.</mixed-citation></ref><ref id="bb5"><mixed-citation publication-type="other">Batisai, E., Su, H. & Nassimbeni, L. R. (2016). <italic>CrystEngComm</italic>, <bold>18</bold>, 5952–5958.</mixed-citation></ref><ref id="bb6"><mixed-citation publication-type="other">Batsanov, A. S. (2018). <italic>Acta Cryst.</italic> E<bold>74</bold>, 570–574.</mixed-citation></ref><ref id="bb7"><mixed-citation publication-type="other">Bondi, A. (1964). <italic>J. Phys. Chem.</italic><bold>68</bold>, 441–451.</mixed-citation></ref><ref id="bb8"><mixed-citation publication-type="other">Bowes, K. F., Glidewell, C. & Low, J. N. (2002). <italic>Acta Cryst.</italic> C<bold>58</bold>, o409–o415.</mixed-citation></ref><ref id="bb9"><mixed-citation publication-type="other">Bruno, I. J., Cole, J. C., Edgington, P. R., Kessler, M., Macrae, C. F., McCabe, P., Pearson, J. & Taylor, R. (2002). <italic>Acta Cryst.</italic> B<bold>58</bold>, 389–397.</mixed-citation></ref><ref id="bb10"><mixed-citation publication-type="other">Dobrzycki, L. (2018). <italic>Z. Kristallogr. Cryst. Mater.</italic><bold>233</bold>, 41–49.</mixed-citation></ref><ref id="bb11"><mixed-citation publication-type="other">Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). <italic>J. Appl. Cryst.</italic><bold>42</bold>, 339–341.</mixed-citation></ref><ref id="bb12"><mixed-citation publication-type="other">Eckardt, K., Paulus, H., Fuess, H., Onoda-Yamamuro, N., Ikeda, R. & Weiss, A. (1999). <italic>J. Inclusion Phenom. Macrocycl. Chem.</italic><bold>35</bold>, 431–449.</mixed-citation></ref><ref id="bb13"><mixed-citation publication-type="other">Ferguson, G., Gallagher, J. F., Glidewell, C., Low, J. N. & Scrimgeour, S. N. (1992). <italic>Acta Cryst.</italic> C<bold>48</bold>, 1272–1275.</mixed-citation></ref><ref id="bb14"><mixed-citation publication-type="other">Ferguson, G., Glidewell, C. & Zakaria, C. M. (1994). <italic>Acta Cryst.</italic> C<bold>50</bold>, 928–931.</mixed-citation></ref><ref id="bb15"><mixed-citation publication-type="other">Flapan, E. (1995). <italic>J. Mol. Struct. (Theochem)</italic>, <bold>336</bold>, 157–164.</mixed-citation></ref><ref id="bb16"><mixed-citation publication-type="other">Glidewell, C. & Ferguson, G. (1994). <italic>Acta Cryst.</italic> C<bold>50</bold>, 924–928.</mixed-citation></ref><ref id="bb17"><mixed-citation publication-type="other">Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). <italic>Acta Cryst.</italic> B<bold>72</bold>, 171–179.</mixed-citation></ref><ref id="bb18"><mixed-citation publication-type="other">Khrustalev, V. N., Borisova, I. V., Zemlyansky, N. N. & Antipin, M. Y. (2009). <italic>Acta Cryst.</italic> C<bold>65</bold>, o31–o34.</mixed-citation></ref><ref id="bb19"><mixed-citation publication-type="other">Lommerse, J. P. M., Stone, A. J., Taylor, R. & Allen, F. H. (1996). <italic>J. Am. Chem. Soc.</italic><bold>118</bold>, 3108–3116.</mixed-citation></ref><ref id="bb20"><mixed-citation publication-type="other">Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). <italic>J. Appl. Cryst.</italic><bold>41</bold>, 466–470.</mixed-citation></ref><ref id="bb21"><mixed-citation publication-type="other">Majerz, I. & Natkaniec, I. (2006). <italic>J. Mol. Struct.</italic><bold>788</bold>, 93–101.</mixed-citation></ref><ref id="bb22"><mixed-citation publication-type="other">Malarski, Z. (1974). <italic>Mol. Cryst. Liq. Cryst.</italic><bold>25</bold>, 259–272.</mixed-citation></ref><ref id="bb23"><mixed-citation publication-type="other">Mootz, D. & Stäben, D. (1993). <italic>Z. Naturforsch. Teil B</italic>, <bold>48</bold>, 1325–1330.</mixed-citation></ref><ref id="bb24"><mixed-citation publication-type="other">Motherwell, W. D. S., Shields, G. P. & Allen, F. H. (1999). <italic>Acta Cryst.</italic> B<bold>55</bold>, 1044–1056.</mixed-citation></ref><ref id="bb25"><mixed-citation publication-type="other">OriginLab (2012). <italic>OriginPro 9.1</italic>. OriginLab Corporation, Northampton, MA, USA.</mixed-citation></ref><ref id="bb26"><mixed-citation publication-type="other">Sasaki, T., Ida, Y., Isaki, I., Yuge, T., Uchida, Y., Tohnai, N. & Miyata, M. (2014). <italic>Chem. Eur. J.</italic><bold>20</bold>, 2478–2487.</mixed-citation></ref><ref id="bb27"><mixed-citation publication-type="other">Schröder, L., Watkin, D. J., Cousson, A., Cooper, R. I. & Paulus, W. (2004). <italic>J. Appl. Cryst.</italic><bold>37</bold>, 545–550.</mixed-citation></ref><ref id="bb28"><mixed-citation publication-type="other">Schulz, A., Villinger, A. & Westenkirchner, A. (2013). <italic>Inorg. Chem.</italic><bold>52</bold>, 11457–11468.</mixed-citation></ref><ref id="bb29"><mixed-citation publication-type="other">Serrano-González, H., Harris, K. D. M., Wilson, C. C., Aliev, A. E., Kitchin, S. J., Kariuki, B. M., Bach-Vergés, M., Glidewell, C., MacLean, E. J. & Kagunya, W. W. (1999). <italic>J. Phys. Chem. B</italic>, <bold>103</bold>, 6215–6223.</mixed-citation></ref><ref id="bb30"><mixed-citation publication-type="other">Sheldrick, G. M. (2008). <italic>Acta Cryst.</italic> A<bold>64</bold>, 112–122.</mixed-citation></ref><ref id="bb31"><mixed-citation publication-type="other">Sheldrick, G. M. (2015<italic>a</italic>). <italic>Acta Cryst.</italic> A<bold>71</bold>, 3–8.</mixed-citation></ref><ref id="bb32"><mixed-citation publication-type="other">Sheldrick, G. M. (2015<italic>b</italic>). <italic>Acta Cryst.</italic> C<bold>71</bold>, 3–8.</mixed-citation></ref><ref id="bb33"><mixed-citation publication-type="other">Steiner, T. (2000). <italic>Acta Cryst.</italic> C<bold>56</bold>, 1033–1034.</mixed-citation></ref><ref id="bb34"><mixed-citation publication-type="other">Stoe & Cie (2018). <italic>X-AREA</italic> and <italic>X-RED32</italic>. Stoe & Cie, Darmstadt, Germany.</mixed-citation></ref><ref id="bb35"><mixed-citation publication-type="other">Thorn, A., Dittrich, B. & Sheldrick, G. M. (2012). <italic>Acta Cryst.</italic> A<bold>68</bold>, 448–451.</mixed-citation></ref><ref id="bb36"><mixed-citation publication-type="other">Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J., Spackman, P. R., Jayatilaka, D. & Spackman, M. A. (2017). <italic>CrystalExplorer17</italic>. University of Western Australia.</mixed-citation></ref><ref id="bb37"><mixed-citation publication-type="other">Weber, E., Skobridis, K. & Goldberg, I. (1989). <italic>J. Chem. Soc. Chem. Commun.</italic> pp. 1195–1197.</mixed-citation></ref><ref id="bb38"><mixed-citation publication-type="other">Westrip, S. P. (2010). <italic>J. Appl. Cryst.</italic><bold>43</bold>, 920–925.</mixed-citation></ref><ref id="bb39"><mixed-citation publication-type="other">Wood, P. A., Allen, F. H. & Pidcock, E. (2009). <italic>CrystEngComm</italic>, <bold>11</bold>, 1563–1571.</mixed-citation></ref><ref id="bb40"><mixed-citation publication-type="other">Zeiss, H. H. & Tsutsui, M. (1953). <italic>J. Am. Chem. Soc.</italic><bold>75</bold>, 897–900.</mixed-citation></ref></ref-list></back><floats-group><fig id="fig1" orientation="portrait" position="float"><label>Figure 1</label><caption><p>Synthetic step from which triphenylmethanol was crystallized. Note that product (<bold>2</bold>) was not obtained.</p></caption><graphic xlink:href="c-75-01266-fig1"></graphic></fig><fig id="fig2" orientation="portrait" position="float"><label>Figure 2</label><caption><p>(Left) Difference electron-density map computed using low-temperature data, after refining the full disordered model but omitting hydroxy H atoms. Grey molecules correspond to the main part <italic>A</italic>/<italic>B</italic> (occupancy 0.74) and gold molecules to the minor part <italic>C</italic>/<italic>D</italic> (occupancy 0.26); hydroxy O atoms are represented with magenta ellipsoids. Two tetramers are displayed in a projection along the threefold crystallographic axis. The difference map is plotted at the 0.33 e Å<sup>−3</sup> level (green wire for Δρ > 0 and red wire for Δρ < 0; Dolomanov <italic>et al.</italic>, 2009<xref ref-type="bibr" rid="bb11"> ▸</xref>). Note how most of the positive residuals are concentrated within the cavity delimited by the eight clustered O atoms. The inset is the crystal used for data collection. Note the triangular face on the top of the crystal, corresponding to the (003) face. (Right) Final model, including 24 disordered hydroxy H atoms, shown as green spheres with a radius corresponding to 33% of the van der Waals radius. All C and O atoms are displayed with displacement ellipsoids at the 20% probability level (<italic>Mercury</italic>; Macrae <italic>et al.</italic>, 2008<xref ref-type="bibr" rid="bb20"> ▸</xref>).</p></caption><graphic xlink:href="c-75-01266-fig2"></graphic></fig><fig id="fig3" orientation="portrait" position="float"><label>Figure 3</label><caption><p>Hydrogen-bonding schemes in the tetramer formed by <italic>A</italic>/<italic>B</italic> molecules. The top figure shows the arrangement of the four molecules and the 12 hydroxy H-atom sites. The left and right panels represent right- (<sup>sup</sup><italic>R</italic>) and left-handed (<sup>sup</sup><italic>S</italic>) supramolecular clusters, respectively. The first figure is oriented down the crystallographic threefold axis and the other is oriented down a noncrystallographic threefold axis. Each cluster comprises six hydrogen bonds (dashed gold bonds), involving six H-atom sites (pink H atoms). Topological graphs <italic>G</italic>(4,6) for supramolecular clusters based on O—H⋯O hydrogen bonds are represented in the centre. Nodes are represented as red balls (O atoms). Arrows forming a ring <italic>R<sub>d</sub><sup>a</sup></italic>(<italic>n</italic>) are stacked over O—H covalent bonds and oriented in the direction <italic>d</italic>→<italic>a</italic>, where <italic>d</italic> is the donor and <italic>a</italic> the acceptor for a hydrogen bond. Arrows involved in a ring are shown in bold, while those not participating in a ring are greyed out. Polygons delimited by <italic>R</italic> rings in the 2-space are coloured yellow and blue for <sup>sup</sup><italic>R</italic> and <sup>sup</sup><italic>S</italic> clusters, respectively, and rings in the projection plane are read clockwise in all cases. For the first-level graphs, <italic>Re</italic> stands for <italic>Rectus</italic> and <italic>Si</italic> for <italic>Sinister</italic>. Note that all figures on the left are mirror images of the figures on the right, including descriptors of the <italic>R</italic> rings.</p></caption><graphic xlink:href="c-75-01266-fig3"></graphic></fig><fig id="fig4" orientation="portrait" position="float"><label>Figure 4</label><caption><p>Complete set of hydrogen bonds, represented as dashed lines, in the tetramer formed by molecules <italic>A</italic> and <italic>B</italic> (left), and in the tetramer formed by molecules <italic>C</italic> and <italic>D</italic> (right). Figures are oriented down the crystallographic threefold axis. Labels (1)⋯(8) on hydrogen bonds indicate the entry in Table 2<xref ref-type="table" rid="table2"> ▸</xref>. Each cluster has four independent bonds, affording 12 bonds for the tetramer, consistent with the <italic>C</italic><sub>3</sub> point symmetry of the tetramer. These figures can be compared to the model published in 1999 (see Fig. 4<xref ref-type="fig" rid="fig4"> ▸</xref> in Serrano-González <italic>et al.</italic>, 1999<xref ref-type="bibr" rid="bb29"> ▸</xref>).</p></caption><graphic xlink:href="c-75-01266-fig4"></graphic></fig><fig id="fig5" orientation="portrait" position="float"><label>Figure 5</label><caption><p>Histogram of the O—H⋯O intermolecular hydrogen-bond geometry in the crystal structures of tertiary alcohols, in spherical polar coordinates (<italic>x</italic>, <italic>y</italic>), with the CSD frequency shown in the third dimension (OriginLab, 2012<xref ref-type="bibr" rid="bb25"> ▸</xref>). A log<sub>10</sub> rainbow colour scheme is used to highlight small frequencies. Some values for the O—H⋯O angles θ are reported on axis <italic>y</italic>, for reference. Note the similarity of the distribution with that depicted in the CCDC article about the directionality of hydrogen bonds (Wood <italic>et al.</italic>, 2009<xref ref-type="bibr" rid="bb39"> ▸</xref>; see Fig. 2<xref ref-type="fig" rid="fig2"> ▸</xref> in this article). The green patch marked with an arrow in the (<italic>x</italic>, <italic>y</italic>) plane defines the area for hydrogen bonds in the <italic>A</italic>/<italic>B</italic> tetrameric cluster of the title compound at 153 K. The inset shows the Hirshfeld surface mapped over <italic>d</italic> (−1 to 1 Å) for the <italic>A</italic>/<italic>B</italic> molecules at 153 K (Turner <italic>et al.</italic>, 2017<xref ref-type="bibr" rid="bb36"> ▸</xref>); each of the four red patches on the surface is related to a single node for the topological graph <italic>G</italic>(4,6) of the <italic>A</italic>/<italic>B</italic> tetramer (see Fig. 3<xref ref-type="fig" rid="fig3"> ▸</xref>).</p></caption><graphic xlink:href="c-75-01266-fig5"></graphic></fig><table-wrap id="table1" orientation="portrait" position="float"><label>Table 1</label><caption><title>Experimental details</title><p>For both determinations: C<sub>19</sub>H<sub>16</sub>O, <italic>M</italic><sub>r</sub> = 260.32, trigonal, <italic>R</italic><inline-formula><inline-graphic xlink:href="c-75-01266-efi1.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>:<italic>H</italic>, <italic>Z</italic> = 24. Experiments were carried out with Ag <italic>K</italic>α radiation (λ = 0.56083 Å) using a Stoe Stadivari diffractometer. Absorption was corrected for by multi-scan methods (<italic>X-AREA</italic>; Stoe & Cie, 2018<xref ref-type="bibr" rid="bb34"> ▸</xref>). Refinement was on 483 parameters. H-atom parameters were constrained.</p></caption><table frame="hsides" rules="groups"><thead valign="top"><tr><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="top"> </th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="top">153 K data</th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="top">295 K data</th></tr></thead><tbody valign="top"><tr><td rowspan="1" colspan="3" align="left" valign="top">Crystal data</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Temperature (K)</td><td rowspan="1" colspan="1" align="left" valign="top">153</td><td rowspan="1" colspan="1" align="left" valign="top">295</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top"><italic>a</italic>, <italic>c</italic> (Å)</td><td rowspan="1" colspan="1" align="left" valign="top">19.1399 (5), 26.7399 (9)</td><td rowspan="1" colspan="1" align="left" valign="top">19.3309 (8), 26.8542 (11)</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top"><italic>V</italic> (Å<sup>3</sup>)</td><td rowspan="1" colspan="1" align="left" valign="top">8483.4 (5)</td><td rowspan="1" colspan="1" align="left" valign="top">8690.5 (8)</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">μ (mm<sup>−1</sup>)</td><td rowspan="1" colspan="1" align="left" valign="top">0.05</td><td rowspan="1" colspan="1" align="left" valign="top">0.05</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Crystal size (mm)</td><td rowspan="1" colspan="1" align="left" valign="top">0.33 × 0.29 × 0.25</td><td rowspan="1" colspan="1" align="left" valign="top">0.38 × 0.33 × 0.33</td></tr><tr><td rowspan="1" colspan="3" align="left" valign="top"> </td></tr><tr><td rowspan="1" colspan="3" align="left" valign="top">Data collection</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top"><italic>T</italic><sub>min</sub>, <italic>T</italic><sub>max</sub></td><td rowspan="1" colspan="1" align="left" valign="top">0.419, 1.000</td><td rowspan="1" colspan="1" align="left" valign="top">0.558, 1.000</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">No. of measured, independent and observed [<italic>I</italic> > 2σ(<italic>I</italic>)] reflections</td><td rowspan="1" colspan="1" align="left" valign="top">99452, 4399, 2222</td><td rowspan="1" colspan="1" align="left" valign="top">72080, 4523, 1656</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top"><italic>R</italic><sub>int</sub></td><td rowspan="1" colspan="1" align="left" valign="top">0.069</td><td rowspan="1" colspan="1" align="left" valign="top">0.108</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">(sin θ/λ)<sub>max</sub> (Å<sup>−1</sup>)</td><td rowspan="1" colspan="1" align="left" valign="top">0.653</td><td rowspan="1" colspan="1" align="left" valign="top">0.653</td></tr><tr><td rowspan="1" colspan="3" align="left" valign="top"> </td></tr><tr><td rowspan="1" colspan="3" align="left" valign="top">Refinement</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top"><italic>R</italic>[<italic>F</italic><sup>2</sup> > 2σ(<italic>F</italic><sup>2</sup>)], <italic>wR</italic>(<italic>F</italic><sup>2</sup>), <italic>S</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.052, 0.167, 1.00</td><td rowspan="1" colspan="1" align="left" valign="top">0.063, 0.242, 0.99</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">No. of reflections</td><td rowspan="1" colspan="1" align="left" valign="top">4399</td><td rowspan="1" colspan="1" align="left" valign="top">4523</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">No. of restraints</td><td rowspan="1" colspan="1" align="left" valign="top">72</td><td rowspan="1" colspan="1" align="left" valign="top">279</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Δρ<sub>max</sub>, Δρ<sub>min</sub> (e Å<sup>−3</sup>)</td><td rowspan="1" colspan="1" align="left" valign="top">0.18, −0.14</td><td rowspan="1" colspan="1" align="left" valign="top">0.11, −0.14</td></tr></tbody></table><table-wrap-foot><p>Computer programs: <italic>X-AREA</italic> (Stoe & Cie, 2018<xref ref-type="bibr" rid="bb34"> ▸</xref>), <italic>SHELXT2018</italic> (Sheldrick, 2015<italic>a</italic><xref ref-type="bibr" rid="bb31"> ▸</xref>), <italic>SHELXL2018</italic> (Sheldrick, 2015<italic>b</italic><xref ref-type="bibr" rid="bb32"> ▸</xref>), <italic>XP</italic> in <italic>SHELXTL-Plus</italic> (Sheldrick, 2008<xref ref-type="bibr" rid="bb30"> ▸</xref>), <italic>Mercury</italic> (Macrae <italic>et al.</italic>, 2008<xref ref-type="bibr" rid="bb20"> ▸</xref>), <italic>OLEX2</italic> (Dolomanov <italic>et al.</italic>, 2009<xref ref-type="bibr" rid="bb11"> ▸</xref>) and <italic>publCIF</italic> (Westrip, 2010<xref ref-type="bibr" rid="bb38"> ▸</xref>).</p></table-wrap-foot></table-wrap><table-wrap id="table2" orientation="portrait" position="float"><label>Table 2</label><caption><title>Hydrogen-bond geometry (Å, °) for the 153 K<xref ref-type="chem" rid="scheme1"></xref> data</title></caption><table frame="hsides" rules="groups"><thead valign="bottom"><tr><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>—H⋯<italic>A</italic></th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>—H</th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom">H⋯<italic>A</italic></th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>⋯<italic>A</italic></th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>—H⋯<italic>A</italic></th></tr></thead><tbody valign="top"><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>A</italic>—H1<italic>A</italic>⋯O1<italic>B</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.85</td><td rowspan="1" colspan="1" align="left" valign="top">2.33</td><td rowspan="1" colspan="1" align="left" valign="top">2.869 (3)</td><td rowspan="1" colspan="1" align="left" valign="top">121</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>B</italic>—H1<italic>BA</italic>⋯O1<italic>A</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.84</td><td rowspan="1" colspan="1" align="left" valign="top">2.27</td><td rowspan="1" colspan="1" align="left" valign="top">2.869 (3)</td><td rowspan="1" colspan="1" align="left" valign="top">129</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>B</italic>—H1<italic>BB</italic>⋯O1<italic>B</italic><sup>i</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.82</td><td rowspan="1" colspan="1" align="left" valign="top">2.21</td><td rowspan="1" colspan="1" align="left" valign="top">2.869 (3)</td><td rowspan="1" colspan="1" align="left" valign="top">138</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>B</italic>—H1<italic>BC</italic>⋯O1<italic>B</italic><sup>ii</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.86</td><td rowspan="1" colspan="1" align="left" valign="top">2.24</td><td rowspan="1" colspan="1" align="left" valign="top">2.869 (3)</td><td rowspan="1" colspan="1" align="left" valign="top">130</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>C</italic>—H1<italic>C</italic>⋯O1<italic>D</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.85</td><td rowspan="1" colspan="1" align="left" valign="top">2.22</td><td rowspan="1" colspan="1" align="left" valign="top">2.856 (7)</td><td rowspan="1" colspan="1" align="left" valign="top">131</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>D</italic>—H1<italic>DA</italic>⋯O1<italic>C</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.84</td><td rowspan="1" colspan="1" align="left" valign="top">2.24</td><td rowspan="1" colspan="1" align="left" valign="top">2.856 (7)</td><td rowspan="1" colspan="1" align="left" valign="top">131</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>D</italic>—H1<italic>DB</italic>⋯O1<italic>D</italic><sup>ii</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.82</td><td rowspan="1" colspan="1" align="left" valign="top">2.38</td><td rowspan="1" colspan="1" align="left" valign="top">2.951 (8)</td><td rowspan="1" colspan="1" align="left" valign="top">127</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>D</italic>—H1<italic>DC</italic>⋯O1<italic>D</italic><sup>i</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.85</td><td rowspan="1" colspan="1" align="left" valign="top">2.33</td><td rowspan="1" colspan="1" align="left" valign="top">2.951 (8)</td><td rowspan="1" colspan="1" align="left" valign="top">131</td></tr></tbody></table><table-wrap-foot><p>Symmetry codes: (i) <inline-formula><inline-graphic xlink:href="c-75-01266-efi15.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>; (ii) <inline-formula><inline-graphic xlink:href="c-75-01266-efi16.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>.</p></table-wrap-foot></table-wrap><table-wrap id="table3" orientation="portrait" position="float"><label>Table 3</label><caption><title>Hydrogen-bond geometry (Å, °) for the 295 K data<xref ref-type="chem" rid="scheme1"></xref></title></caption><table frame="hsides" rules="groups"><thead valign="bottom"><tr><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>—H⋯<italic>A</italic></th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>—H</th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom">H⋯<italic>A</italic></th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>⋯<italic>A</italic></th><th style="border-bottom:1px solid black;" rowspan="1" colspan="1" align="left" valign="bottom"><italic>D</italic>—H⋯<italic>A</italic></th></tr></thead><tbody valign="top"><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>A</italic>—H1<italic>A</italic>⋯O1<italic>B</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.85</td><td rowspan="1" colspan="1" align="left" valign="top">2.56</td><td rowspan="1" colspan="1" align="left" valign="top">2.917 (3)</td><td rowspan="1" colspan="1" align="left" valign="top">106</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>B</italic>—H1<italic>BA</italic>⋯O1<italic>A</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.82</td><td rowspan="1" colspan="1" align="left" valign="top">2.27</td><td rowspan="1" colspan="1" align="left" valign="top">2.917 (3)</td><td rowspan="1" colspan="1" align="left" valign="top">136</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>B</italic>—H1<italic>BB</italic>⋯O1<italic>B</italic><sup>i</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.82</td><td rowspan="1" colspan="1" align="left" valign="top">2.31</td><td rowspan="1" colspan="1" align="left" valign="top">2.912 (3)</td><td rowspan="1" colspan="1" align="left" valign="top">131</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>B</italic>—H1<italic>BC</italic>⋯O1<italic>B</italic><sup>ii</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.85</td><td rowspan="1" colspan="1" align="left" valign="top">2.31</td><td rowspan="1" colspan="1" align="left" valign="top">2.912 (4)</td><td rowspan="1" colspan="1" align="left" valign="top">128</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>C</italic>—H1<italic>C</italic>⋯O1<italic>D</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.85</td><td rowspan="1" colspan="1" align="left" valign="top">2.27</td><td rowspan="1" colspan="1" align="left" valign="top">2.916 (13)</td><td rowspan="1" colspan="1" align="left" valign="top">133</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>D</italic>—H1<italic>DA</italic>⋯O1<italic>C</italic></td><td rowspan="1" colspan="1" align="left" valign="top">0.83</td><td rowspan="1" colspan="1" align="left" valign="top">2.26</td><td rowspan="1" colspan="1" align="left" valign="top">2.916 (13)</td><td rowspan="1" colspan="1" align="left" valign="top">136</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>D</italic>—H1<italic>DB</italic>⋯O1<italic>D</italic><sup>ii</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.83</td><td rowspan="1" colspan="1" align="left" valign="top">2.35</td><td rowspan="1" colspan="1" align="left" valign="top">2.947 (13)</td><td rowspan="1" colspan="1" align="left" valign="top">130</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">O1<italic>D</italic>—H1<italic>DC</italic>⋯O1<italic>D</italic><sup>i</sup></td><td rowspan="1" colspan="1" align="left" valign="top">0.84</td><td rowspan="1" colspan="1" align="left" valign="top">2.33</td><td rowspan="1" colspan="1" align="left" valign="top">2.947 (13)</td><td rowspan="1" colspan="1" align="left" valign="top">132</td></tr></tbody></table><table-wrap-foot><p>Symmetry codes: (i) <inline-formula><inline-graphic xlink:href="c-75-01266-efi15.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>; (ii) <inline-formula><inline-graphic xlink:href="c-75-01266-efi16.jpg" mimetype="image" mime-subtype="gif"></inline-graphic></inline-formula>.</p></table-wrap-foot></table-wrap><table-wrap id="table4" orientation="portrait" position="float"><label>Table 4</label><caption><title>Comparison between the three X-ray structures of triphenylmethanol determined at room temperature</title></caption><table frame="hsides" rules="groups"><tbody valign="top"><tr><td rowspan="1" colspan="1" align="left" valign="top">Date of publication</td><td rowspan="1" colspan="1" align="left" valign="top">1992<sup><italic>a</italic></sup></td><td rowspan="1" colspan="1" align="left" valign="top">1999<sup><italic>b</italic></sup></td><td rowspan="1" colspan="1" align="left" valign="top">2019<sup><italic>c</italic></sup></td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Diffractometer</td><td rowspan="1" colspan="1" align="left" valign="top">CAD-4</td><td rowspan="1" colspan="1" align="left" valign="top">R-Axis II</td><td rowspan="1" colspan="1" align="left" valign="top">Stadivari</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Detector</td><td rowspan="1" colspan="1" align="left" valign="top">NaI scintillator</td><td rowspan="1" colspan="1" align="left" valign="top">Image plate</td><td rowspan="1" colspan="1" align="left" valign="top">HPAD<sup><italic>d</italic></sup></td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top"><italic>T</italic> (K)</td><td rowspan="1" colspan="1" align="left" valign="top">294</td><td rowspan="1" colspan="1" align="left" valign="top">293</td><td rowspan="1" colspan="1" align="left" valign="top">295</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">No. independent reflections</td><td rowspan="1" colspan="1" align="left" valign="top">2467</td><td rowspan="1" colspan="1" align="left" valign="top">3448</td><td rowspan="1" colspan="1" align="left" valign="top">4523</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Refined parameters</td><td rowspan="1" colspan="1" align="left" valign="top">253</td><td rowspan="1" colspan="1" align="left" valign="top">322</td><td rowspan="1" colspan="1" align="left" valign="top">483</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Data resolution (Å)</td><td rowspan="1" colspan="1" align="left" valign="top">0.89</td><td rowspan="1" colspan="1" align="left" valign="top">0.82</td><td rowspan="1" colspan="1" align="left" valign="top">0.77</td></tr><tr><td rowspan="1" colspan="1" align="left" valign="top">Range for σ(C—C)</td><td rowspan="1" colspan="1" align="left" valign="top">0.040–0.007 Å</td><td rowspan="1" colspan="1" align="left" valign="top">–</td><td rowspan="1" colspan="1" align="left" valign="top">0.020–0.003 Å</td></tr></tbody></table><table-wrap-foot><p>Notes and references: (<italic>a</italic>) Ferguson <italic>et al.</italic> (1992<xref ref-type="bibr" rid="bb13"> ▸</xref>); (<italic>b</italic>) Serrano-González <italic>et al.</italic> (1999<xref ref-type="bibr" rid="bb29"> ▸</xref>); (<italic>c</italic>) this work; (<italic>d</italic>) Hybrid Pixel Array Detector.</p></table-wrap-foot></table-wrap></floats-group></pmc></record>Pour manipuler ce document sous Unix (Dilib)
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