Ab initio SCF-MO study on difluoromethanediol and difluorodimethoxymethane

Abstract

Difluoromethanediol and difluorodimethoxymethane systems have been investigated by ab initio molecular orbital methods using STO-3G and 4-31G basis sets. The potential energy surfaces for both systems have been constructed and compared with those of methanediol and dimethoxymethane, respectively. Difluoromethanediol favours (180°, 0°) as the minimum energy conformation whereas difluorodimethoxymethane favours (180°, 60°). However, after bond angle optimization difluorodimethoxymethane favours (180°, 180°) conformation. A comparison of the minimum energy conformations of phosphates, sulfates and methanediol with that of difluoromethanediol has been made. Bond length optimization reveals very short C---F and C---O bonds in difluoromethanediol. Decomposition of the potential function V(ø₁) using a three-term truncated Fourier expression shows that the V₁ term becomes less important in difluoromethanediol, when compared with the methanediol system.