Comparative G2(MP2) molecular orbital study of [H3AlX(CH3)(2)](-) (X = N, P, and As) and H3AlY(CH3)(2) (Y = O, S, and Se) donor-acceptor complexes

[H3AlX(CH3)(2)](-) (X = N, P, and As) and H3AlY(CH3)(2) (Y = O, S, and Se) donor-acceptor complexes have been studied using G2(MP2) level of theory. T he coordination mode, the structural and the methyl substitution effects up on complexation are analyzed. The interaction of the alane with the donor l igand is stronger in the anionic complexes than in the neutral ones and the methylated complexes are more stable than the hydrogenated ones. The coord ination is ensured by tow interactions having a reverse character: interact ion between a' symmetry fragment molecular orbital (stabilizing) and intera ction between a " symmetry occupied molecular orbital (destabilizing) of th e two fragments. A linear correlation has been established and discussed be tween the energetic and the structural effects upon methylation. The NBO pa rtitioning scheme suggests that there is no correlation between the charge transfer and the G2(MP2) complexation energy. (C) 2001 Elsevier Science B.V . All rights reserved.