Methyl tunnelling in pure and matrix isolated halogenomesitylenes

摘要: Abstract The trihalogenomesitylenes, C6(CH3)3X3, where X = Cl, Br, I crystallise in the triclinic P 1 space- group, such that three methyl groups one molecule see different environments. Indeed, we have detected tunnelling and torsional transitions pure compounds. In case of a 3.7% mixture protonated tribromomesitylene matrix hexabromobenzene, only transition at 102μeV; from this, conclude TBM dilute are equivalent what is relatively symmetrical environment as consequence also isolated molecule. A solid solution 6% fully trichloromesitylene deuterated TCM gives similar to those compound, indicating there no strong coupling between groups. We present Raman FIR spectra giving phonon frequencies Γ point. Some IR absorption maxima fall near neutron spectra, some phonons transitions. So give us model system optimised atom-atom Buckingham-type coefficients so reproduce experimental frequencies. were used calculate intermolecular contribution Vex(θ) Vs(θ), potential hindering intramolecular Vin(θ) was found using quantum chemistry program AM1. total Vs(θ) obtained allowed principal dynamic features rotors reasonable agreement with experiments.