PM3 SEMIEMPIRICAL CALCULATIONS OF LITHIUM-CATION AND PROTON AFFINITIES FOR XYZPO AND XYSO(2) COMPOUNDS

Proton affinities (PAs) of a series of phosphorous compounds bearing t he phosphoryl function have been calculated using AM1 and PM3, as well as lithium-cation affinities (LCAs) using the recent PM3 lithium para metrization. Sulfonyl derivatives PAs and LCAs have been also calculat ed using PM3. The Li+ cation can be bonded in a ''chelate'' form with the two oxygens of the sulfonyl group. Nevertheless, the ''linear'' ad duct, with the lithium-oxygen bond collinear with one of the S=O bonds , is more stable. This is confirmed by ab initio calculations on Me(2) SO(2)-Li+ adducts. (C) 1996 John Wiley & Sons, Inc.