Analysis of Bonding in Cyclopentadienyl Transition-Metal Boryl Complexes

Abstract

Analysis of the bonding in transition-metal boryl complexes of the type [(C5R5)M(CO)2BX2] has been carried out by density functional methods, to quantify the relative contributions to the metal boryl linkage from ionic and covalent interactions. Covalent (orbital) terms account for 60−70% of the overall attractive interaction between metal and boryl fragments, with σ donation from the boryl ligand overwhelmingly predominating over π back-donation even in the most favorable cases (e.g. 84.1:15.8 and 81.9:18.0 for CpFe(CO)2BH2 and CpFe(CO)2B(C6F5)2, respectively).