Electronic structure and metal–metal communication in (CpM)2(as-indacene) and (CpM)2(s-indacene) (M = Mn, Fe, Co, Ni) complexes: a DFT investigationThis paper is dedicated to an outstanding chemist, our friend Didier Astruc, on the occasion of his 65th birthday.

DFT calculations with full geometry optimization have been performed on the series (CpM)2(as-indacene) and (CpM)2(s-indacene) (M = Mn, Fe, Co, Ni), as well as on the cations of the Fe, Co and Ni complexes. The compounds where M = Fe and Ni (as-indacene series) and M = Mn, Fe and Co (s-indacene series) were found to possess closed-shell ground states. In the mixed-valent cations as well as in the other open-shell species, the degree of metal–metal communication and the participation of the ligand into the spin density were evaluated. In general, the larger the total electron number, the larger the metal–metal communication and ligand participation to the frontier orbitals. [ABSTRACT FROM AUTHOR]