Central‐Atom Size Effects on the Methyl Torsions of Group XIV Tetratolyls |
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| Authors: | Dr Maggie C C Ng Dr Jason B Harper Dr Anton P J Stampfl Prof Gordon J Kearley Dr Stéphane Rols Prof John A Stride |
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| Institution: | 1. School of Chemistry, University of New South Wales, Sydney 2052 (Australia), Fax: (+61)?2‐9385‐6141;2. Bragg Institute, Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia);3. Institute Laue‐Langevin, 6 rue Jules Horowitz, BP156, 38042 Grenoble Cedex 9 (France) |
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| Abstract: | The Group XIV tetratolyl series X(C6H4‐CH3)4 (X=C, Si, Ge, Sn, Pb) were studied by using inelastic neutron scattering to measure the low‐energy phonon spectra to directly access the methyl‐group torsional modes. The effect of increased molecular radius as a function of the size of the central atom was shown to have direct influence on the methyl dynamics, reinforced with the findings of molecular dynamics and contact surface calculations, based upon the solid‐state structures. The torsional modes in the lightest analogue were found to be predominantly intramolecular: the Si and Ge analogues have a high degree of intermolecular methyl–methyl group interactions, whilst the heaviest analogues (Sn and Pb) showed pronounced intermolecular methyl interactions with the whole phonon bath of the lattice modes. |
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| Keywords: | crystal engineering density functional calculations intermolecular interactions molecular dynamics neutron scattering |
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