The comparison of structure, nature of bond, and electronic transitions in [M(η5-Cp)(η5-C60Me5)] (M = Fe2+, Ru2+, Os2+) hybrids and corresponding metallocenes; a theoretical study

In this paper, metallocene-fullerene hybrid complexes, [M(eta(5)-Cp)(eta(5)-C60Me5)] (M = Fe2+, Ru2+, Os2+), as well as corresponding classical metallocenes have been studied theoretically at BP86/def2-SVP and M06L/def2-SVP levels of theory. With considering these metal complexes as an ABA ' system (B is the central metal ion and A and A ' are related eta(5)-ligands), the total interaction energies were calculated using common methods, as well as by calculating the interaction energies between the four defined pairs of fragments including A-B, B-A ', A-BA ', and AB-A '. The resulting data clearly showed that in all complexes there is a strong anticoopertivity between two metal-(eta(5)-ligand) bonds. In order to understand the origin of difference in values of various calculated interactions in above two types of complexes, the nature of metal-ligand bonds was also studied using energy decomposition analysis-natural orbital for chemical valence calculations. The results showed that in hybrid complexes, in contrast to metallocenes, the orbital interactions are considerably larger than electrostatic interactions.