VIBRATIONAL-SPECTRA AND STRUCTURE OF TRIMETHYLINDIUM AND TRIMETHYLTHALLIUM

A detailed vibrational spectrum of trimethylthallium is reported for t he first time (Raman spectra of the melt and crystal, IR spectra of cr ystalline, gaseous and matrix-isolated samples). Analogous data were a lso obtained for trimethylindium for comparison. In the Raman spectra of both compounds in the liquid state some peculiarities are found whi ch suggest low-barrier hindered rotation of the methyl groups. Some fe atures in the spectra of trimethylthallium and triethylthallium distin guish these compounds from their In and Ga analogues, and could be int erpreted as arguments in favour of distortion of the planar TlC3 skele ton in condensed phases, probably as a result of the pseudo-Jahn-Telle r effect. (C) 1997 Published by Elsevier Science S.A.