Molecular orbital study of the electron donor-acceptor properties of the P atom in Ni(PX3)4 (X=H, F, Cl) complexes

Abstract A comparative study of the Ni(PH 3 ) 4 , Ni(PF 3 ) 4 and Ni(PCl 3 ) 4 complexes was carried out using the self-consistent field (SCF) multiple scattering method. Ab initio calculations were also performed for the model system L-Ni-PF 3 (L=CO, N 2 ) in order to study the σ-π donor-acceptor capabilities of PF 3 , CO and N 2 . The results show the importance of π bonding between the Ni and P atoms. However, it is found that it is the P 3p rather than the P 3d orbital which forms a bond with the Ni 3d orbital. The correlation between the σ-donor and π-acceptor capabilities and the electronegativity of the P ligands is also analysed in detail. Our present results give further support to the analogy between the transition metal-P bond and the hyperconjugation bond in organic compounds.