Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, and trimethylgermyl derivatives of 3,3-dimethylcyclopropene.: I.: 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene

The geometrical parameters of 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene were optimised completely at the HF/63 31G* level. The HF/6-31G*//HF/6-31G* force field was calculated and scaled using Pulay's scaling procedure. The set of 17 scale factors (for a 105-dimensional problem) was compiled from the sets obtained previously for 3,3-dimethyl-1-butene and 1-methyl-, 1,2-dimethyl-, and 3,3-dimethylcyclopropene. The vibrational problem was solved using the scaled quantum mechanical force field (QMFF) and assignments of the vibrational frequencies of 3,3-dimethyl-1,2bis(tert-butyl)cyclopropene were considered in comparison with the known assignments of 3,3-dimethyl-1-butene and 3,3-dimethylcyclopropene. Assignments of four experimental IR bands of 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene given in the literature are suggested. (C) 2002 Elsevier Science B.V. All rights reserved.