Alkali Metal Covalent Bonding in Nickel Carbonyl Complexes ENi(CO)₃⁻

Abstract

Abstract The alkali metal‐nickel carbonyl anions ENi(CO) 3 − with E=Li, Na, K, Rb, Cs have been produced and characterized by mass‐selected infrared photodissociation spectroscopy in the gas phase. The molecules are the first examples of 18‐electron transition metal complexes with alkali atoms as covalently bonded ligands. The calculated equilibrium structures possess C 3 v geometry, where the alkali atom is located above a nearly planar Ni(CO) 3 − fragment. The analysis of the electronic structure reveals a peculiar bonding situation where the alkali atom is covalently bonded not only to Ni but also to the carbon atoms.