Ferrocene analogues of sandwich M(CrB6H6)2: a theoretical investigation

Abstract

The stability and electronic structures of the new sandwich compounds M(CrB₆H₆)₂ (M = Cr, Mn⁺, Fe²⁺) are investigated by density functional theory. All the investigated sandwich complexes are in D_6d symmetry and all of them are thermodynamically stable according to the large HOMO–LUMO gap, binding energy, vertical ionization potential and vertical electron affinity analyses, as well as Fe(C₅H₅)₂ and Cr(C₆H₆)₂, following the 18-electron principle. The natural bond orbital, detailed molecular orbitals and adaptive natural density partitioning analyses suggest that the spd–π interaction plays an important role in the sandwich compounds. This work challenges the traditional chemical bonding of the inorganic metal compound, investigates first the bonding style of the d atom orbital interacting with the π MO which was formed by p–d atomic orbitals, and indicates that the metal-doped borane ring can also be an ideal type π-electron donor ligand to stabilize the transition metal.