DFT INVESTIGATIONS OF THE STRUCTURE AND BONDING BETWEEN TRANSITION-METALS AND OLEFINS

The structure of ethylene, allyl, and butadiene pi-complexes with Ni-0 and Ni2+ were optimized with density functional theory (DFT). The dif ferent kinds of coordinative interaction between the olefins and the m etal had been discussed for the frontier orbitals of the given symmetr y. Both components of the donation and back-donation bond were charact erized by charge density analysis (CDA) and natural bond orbital (NBO) populations. In case of the butadiene ligand the s-cis and s-trans co nformer and the transition state of their rearrangement were localized and characterized by their vibrational spectra. The calculated ioniza tion of bis(pi-allyl)nickel can be well represented by comparing the D FT energies of the neutral molecule and its cationic configurations (D elta SCF procedure). (C) 1998 John Wiley & Sons, Inc.