Conformational Energies and Structural Relaxation in Singly Bonded Silicon, Phosphorus and Sulfur-Compounds

Abstract

Conformational energy differences, structural relaxation and changes in bonding between different rotamers of silicon, phosphorus and sulfur compounds have been calculated by ab initio molecular orbital methods to permit systematic comparison between the compounds of first and second row elements. The results were obtained with polarized 3-21G and 4-31G basis sets on the series SiH3X, PH2X and SHX (X = BH2, CH3, NH2 and OH) and also on the rotamers of the second row hydrides Si2H6, P2H4 and S2H2. Bond length and bond angle relaxation and conformational energy differences for the Si -, P- and S-containing molecules are 30-50% smaller than in the compounds of the first row elements.