Density functional theory study on structural isomers and bonding of model complexes M(CO)5(BH3• PH3) (M = Cr, Mo, W) and W(CO)5(BH3 • AH3) (A = N, P, As, Sb)

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)(BH3 center dot AH(3)) and M(CO)(5)(BH3 center dot PH3) (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, eta(1), with C-1 point group; (b) in all complexes, the eta(1) isomer with C-s symmetry on potential energy surface is the transition state for oscillating borane; (c) the eta(2) isomer is the transition state for the hydrogens interchange mechanism; (d) in W(CO)(5)(BH3 center dot 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)(BH3 center dot PH3) interaction energy is ordered as M = W > Cr > Mo, while energy barrier for interchanging hydrogens decreases in the order of M = Cr > W > Mo. (c) 2004 Elsevier B.V. All rights reserved.