Density functional theory study on structural isomers and bonding of model complexes M(CO) 5(BH 3 · PH 3) (M = Cr, Mo, W) and W(CO) 5(BH 3 · AH 3) (A = N, P, As, Sb)

Abstract

The influence of group 15 various substituents and effect of metal centers on metal–borane interactions and structural isomers of transition metal–borane complexes W(CO) 5(BH 3 · AH 3) and M(CO) 5(BH 3 · PH 3) (A = N, P, As, and Sb; M = Cr, Mo, and W), were investigated by pure density functional theory at BP86 level. The following results were observed: (a) the ground state is monodentate, η 1, with C 1 point group; (b) in all complexes, the η 1 isomer with C S symmetry on potential energy surface is the transition state for oscillating borane; (c) the η 2 isomer is the transition state for the hydrogens interchange mechanism; (d) in W(CO) 5(BH 3 · AH 3), the degree of pyramidalization at boron, interaction energy as well as charge transfer between metal and boron moieties, energy barrier for interchanging hydrogens, and diffuseness of A increase along the series A = Sb < As < P < N; (e) in M(CO) 5(BH 3 · PH 3), interaction energy is ordered as M = W > Cr > Mo, while energy barrier for interchanging hydrogens decreases in the order of M = Cr > W > Mo.