Order–disorder transitions in substituted adamantanes

Clark, Timothy; Knox, Trevor Mc. O.; Mackle, H.; McKervey, M. Anthony

doi:10.1039/f19777301224

Cited by 62 publications

(56 citation statements)

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“…Adamantane C~oH~6 is a spherical molecule of Td symmetry which undergoes, below its melting point (Tin--541 K), an order-disorder phase transition at Tt = 208.6 K (Clark, Knox, Mackle & Hervey, 1977). Fluoroadamantane C~oH~sF is a globular molecule of C3v symmetry obtained from adamantane by sub- stituting an F atom for one methylene H atom (Fig.…”

Section: Generalmentioning

confidence: 99%

Comparison between structural analyses of plastic and brittle crystals

Amoureux¹,

Foulon²

1987

Acta Crystallogr Sect B

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Section: Generalmentioning

confidence: 99%

Comparison between structural analyses of plastic and brittle crystals

Amoureux¹,

Foulon²

1987

Acta Crystallogr Sect B

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“…The NMR and dielectric relaxation experiments we performed (Amoureux, 1980) had proved that, like adamantane, fluoroadamantane is a plastic crystal at room temperature" between the transition temperature (T t = 221.6 K) and the melting point (T m = 525 K) (Clark, Knox, Mackle & Hervey, 1977).…”

Section: Introductionmentioning

confidence: 99%

Structure of 1-fluoroadamantane, C₁₀H₁₅F, in its plastic phase

Amoureux¹,

Bée²,

Sauvajol³

1982

Acta Crystallogr Sect B

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Single-crystal X-ray diffraction data were collected and interpreted for the plastic phase of 1-fluoroadamantane, C10H15 F at 293K. The unit cell is face-centred cubic with a = 9.535 (4)A, space group Fm3m, Z = 4. On the assumption of a rigid molecular skeleton, several types of orientational disorder were investigated: hindered reorientations between equally weighted orientations, free uniaxial rotation of the molecules about the C-F axis and decomposition of the atomic orientational average density on symmetryadapted functions. With the first and the third models agreement between observed and calculated structure factors is found in which molecular (C-F) and lattice ([ 1111) threefold axes are aligned.

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“…The crystal structure data indicate that the positions of the hydroxyl protons are already disordered and therefore the transition entropy is lowered by at least R In 2. Even allowing for an excess entropy of the type proposed by Clark et al (9), an entropy change of (35 -approx. 10.5) J K-' mol-' is equivalent to a ratio of about l8:l for the ratio of distinguishable positions in the ordered and disordered phases.…”

Section: Resultsmentioning

confidence: 99%

Phase transitions and molecular motions in adamantane derivatives: 1-adamantanol

Harvey¹,

Gilson²,

Butler³

1987

Can. J. Chem.

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An order-disorder transition occurs in 1-adamantanol at 359 K on heating and at 342 K on cooling, with transition entropies of 36 and 34 J K-' mol-I, respectively. R -i r spectra show that free hydroxyl groups exist in the high temperature phase, but the majority of the 0-H groups remain hydrogen bonded. The barrier to adamantyl group rotation in the low-temperature phase, determined from proton spin-lattice relaxation time measurements, is 20.9 kJ mol-I, and the barrier to rotation in the high-temperature phase is 35.0 kJ mol-I. PIERRE D. HARVEY, DENIS F. R. GILSON et IAN S. BUTLER. Can. J. Chem. 65, 1757(1987.Avec l'adamantanol-1, il se produit une transition ordreldCsordre i 359 K lorsqu'on chauffe et A 342 K lorsqu'on refroidit: les entropies de transition sont respectivement 36 et 34 J K-' mol-I. Les spectres ir/TF dCmontrent que des groupements hydroxyles libres existent dans la phase a haute tempkrature; toutefois, des liaisons hydrogknes relient encore la majorit6 des groupements 0-H. Dans la phase i basse tempkrature, la barrikre i i la rotation du groupement adamantyle, telle que dCterminCe i partir des temps de relaxation spinlrCseau des protons, est Cgale 20,9 kJ mol-'; dans la phase h haute temperature, la barrikre i la rotation est Cgale i 35,O kJ mol-I.[Traduit par la revue] IntroductionThe cage hydrocarbon adamantane, C10H16, affords the best known example of an organic molecular crystal which undergoes an order-disorder phase transition. Simple substitution on the adamantyl skeleton does not prevent the transition from occurring, but can lead to a wide variation in the temperature and entropy of the transition. In many cases, the phase transitions occur below room temperature, and, therefore, the crystal structures of the ordered phases are seldom known. One particular exception is 1-adamantanol, in which the transition is reported to occur at 353 K with an entropy change of 40.6

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Order–disorder transitions in substituted adamantanes

Cited by 62 publications

References 0 publications

Comparison between structural analyses of plastic and brittle crystals

Comparison between structural analyses of plastic and brittle crystals

Structure of 1-fluoroadamantane, C₁₀H₁₅F, in its plastic phase

Phase transitions and molecular motions in adamantane derivatives: 1-adamantanol

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Order–disorder transitions in substituted adamantanes

Cited by 62 publications

References 0 publications

Comparison between structural analyses of plastic and brittle crystals

Comparison between structural analyses of plastic and brittle crystals

Structure of 1-fluoroadamantane, C10H15F, in its plastic phase

Phase transitions and molecular motions in adamantane derivatives: 1-adamantanol

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Structure of 1-fluoroadamantane, C₁₀H₁₅F, in its plastic phase