The low-temperature phase III structure and phase transition behaviour of cyclohexanone

Ibberson, R. M.

doi:10.1107/s0108768106015485

Cited by 9 publications

(11 citation statements)

References 23 publications

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“…For example, cyclohexanone, which also adopts a chair conformation, shows a 6% volume discontinuity at the 225 K transition to a plastic f.c.c. phase (Ibberson, 2006). Cyclohexene oxide shows a comparable volume discontinuity of 9%, but in this case the molecule has a halfchair conformation and transforms at 193 K to a disordered simplecubic structure .…”

Section: The Phase I Crystal Structurementioning

confidence: 99%

Polymorphism in cyclohexanol

Ibberson

Parsons

Allan

et al. 2008

Acta Crystallogr Sect B

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Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr.For further information see http://journals.iucr.org/services/authorrights.html Acta Crystallographica Section B: Structural Science publishes papers in structural chemistry and solid-state physics in which structure is the primary focus of the work reported. The central themes are the acquisition of structural knowledge from novel experimental observations or from existing data, the correlation of structural knowledge with physicochemical and other properties, and the application of this knowledge to solve problems in the structural domain. The journal covers metals and alloys, inorganics and minerals, metal-organics and purely organic compounds.Crystallography Journals Online is available from journals.iucr.org Acta Cryst. (2008 The crystal structures and phase behaviour of phase II and the metastable phases III 0 and III of cyclohexanol, C 6 H 11 OH, have been determined using high-resolution neutron powder, synchrotron X-ray powder and single-crystal X-ray diffraction techniques. Cyclohexanol-II is formed by a transition from the plastic phase I cubic structure at 265 K and crystallizes in a tetragonal structure, space group P " 4 42 1 c (Z 0 = 1), in which the molecules are arranged in a hydrogen-bonded tetrameric ring motif. The structures of phases III 0 and III are monoclinic, space groups P2 1 /c (Z 0 = 3) and Pc (Z 0 = 2), respectively, and are characterized by the formation of hydrogen-bonded molecular chains with a threefold-helical and wave-like nature, respectively. Phase III crystallizes at 195 K from a sample of phase I that is supercooled to ca 100 K. Alternatively, phase III may be grown via phase III 0 , the latter transforming from supercooled phase I at ca 200 K. Phase III 0 is particularly unstable and is metastable with respect to both I and II. Its growth is realised only under very restricted conditions, thus making its characterization especially challenging. The cyclohexanol molecules adopt a chair conformation in all three phases with the hydroxyl groups in an equatorial orientation. No evidence was found indicating hydroxyl groups adopting an axial orientation, contrary to the majority of spectroscopic literature on solid-state cyclohexanol; however, the H atom of the equatorial OH groups is found to adopt both in-plane and out-of-plane orientations.

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Section: The Phase I Crystal Structurementioning

confidence: 99%

Polymorphism in cyclohexanol

Ibberson

Parsons

Allan

et al. 2008

Acta Crystallogr Sect B

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“…Similar arrangements of CH molecules were observed in one of the solid phases of pure CH. 7 In spite of the anti-parallel orientation of carbonyl groups in a pair the overlapping of p-systems is not ideal -the shortest inter-carbonyl contact is C1 … C1 (2x, 1 2 y, 2z) 3.680 (8) and CH molecules. Pairs of these interactions link molecules into a heterotetramer, shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Low-melting molecular complexes. Halogen bonds in molecular complexes of bromoform

et al. 2012

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Single crystals of three new low-melting molecular complexes of bromoform have been grown in situ, their crystal structures characterized by X-ray crystallography and compared with those of their chloroform analogues. The calculations of pair-wise energies of intermolecular interactions in these structures reveal that in some cases the strongest interactions exist between the molecules which are not linked by any short direction-specific intermolecular contacts. A high versatility of bonding modes of bromoform in comparison to chloroform is demonstrated and the relative role of various intermolecular interactions (including halogen bonds) in studied molecular complexes is discussed.

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“…Below the melting point of 245 K, cyclohexanone forms a face‐centered, cubic, plastic crystal of the space group

F m \overline{3} m

. However, on cooling to below 225 K, the crystal transforms to the ordered, monoclinic, Phase III structure of the space group P2 1 /n . (The orthorhombic Phase II exists under high pressure, but the triple point for all three phases is close to ambient pressure).…”

Section: Resultsmentioning

confidence: 99%

Comprehensive Vibrational Spectroscopic Characterization of Nylon‐6 Precursors for Precise Tracking of the Beckmann Rearrangement

et al. 2018

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As a key step in nylon‐6 synthesis, the Beckmann rearrangement is an ongoing target of catalytic studies that seek to improve the sustainability of polymer manufacture. Whilst solid‐acid catalysts (predominantly zeotypes) have proven effective for this transformation, the development of more active and selective systems demands an understanding of fundamental catalytic mechanisms. In this undertaking, in situ and operando characterization techniques can be informative, provided rigorous spectroscopic groundwork is in place. Thus, to facilitate mechanistic studies we present a detailed investigation of the vibrational spectra of cyclohexanone, cyclohexanone oxime, ϵ‐caprolactam and their D10‐isotopomers, in the solid state. Variable‐temperature infrared (150–300 K) and Raman (10–300 K) spectra are reported alongside inelastic neutron scattering data. Moreover, where key vibrational modes have been assigned with the aid of periodic density functional theory calculations, it has been possible to include hydrogen‐bonding interactions explicitly.

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The low-temperature phase III structure and phase transition behaviour of cyclohexanone

Cited by 9 publications

References 23 publications

Polymorphism in cyclohexanol

Polymorphism in cyclohexanol

Low-melting molecular complexes. Halogen bonds in molecular complexes of bromoform

Comprehensive Vibrational Spectroscopic Characterization of Nylon‐6 Precursors for Precise Tracking of the Beckmann Rearrangement

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