Structure and bonding analysis in dihalobismuth complexes of iron, ruthenium and osmium [(η5-C5H5)(CO)2M(BiX2)]: A theoretical study

Abstract

Density functional theory (DFT) calculations have been performed to investigate the nature of the M–Bi bonds in dihalobismuth complexes of iron, ruthenium and osmium, [(η5-C5H5)(CO)2M(BiX2)] (M=Fe, Ru, Os; X=Cl, Br, I) and [(η5-C5H5)(PMe3)2Fe(BiX2)] (X=Cl, Br, I), at the BP86/TZ2P/ZORA level of theory. Pauling and Mayer bond orders of the optimized structures show that the M-Bi bonds in these complexes are nearly M–Bi single bonds. The π bonding contribution is, in all complexes, significantly smaller than the corresponding σ bonding contribution, representing only 5–14% of the total orbital interaction. Thus, in these complexes, [BiX2] behaves predominantly as σ donor. The values of the Mayer bond order of the M–Bi bonds in dihalobismuth complexes suggest a significant covalent contribution to the M–Bi bonds. These observations are supported by the greater contributions of the covalent interaction energy ΔEorb than the electrostatic interactions ΔEelstat in all the dihalobismuth complexes. The absolute values of the ΔEint, ΔEorb and ΔEelstat contributions to the M–Bi bonds decrease according to X=Cl>Br>I, while the values of these energy terms increases in all four sets of complexes in the order Fe<Ru<Os. Upon substitution of the auxiliary CO ligand with the PMe3 ligand, the ΔEint, ΔEorb and ΔEelstat contributions increase.