Ab Initio Study on Mixed Inorganic/Organic Ligand Sandwich Clusters: BzTMC60, TM = Sc-Co

We have systematically investigated mixed inorganic/organic ligand sandwich clusters comprised of 3d transition metal (TM) atoms with C-60 and benzene (Bz) molecules, BzTMC(60), by using all electron density functional theory. We found the bonding type between TM and C-60 in the ground state evolves from eta(6) (TM = Sc-Cr) to eta(5) (TM = Mn) and then to eta(2) (TM = Fe, Co) with increasing number of d electrons of TM. The BzTMC(60) clusters (TM = Sc-Co) are of high stability through ionic-covalent interactions. The BzCrC(60) cluster has the lowest binding energy due to its largest spin-flip energy and the weakest ionic bonding interaction between the CrBz unit and C-60. With the exception of BzTiC(60) being triplet, all the BzTMC(60) clusters energetically prefer the lowest available spin states, e.g., the ground spin state is either a singlet (with an even number of electrons) or a doublet (with an odd number of electrons). Moreover, the magnetic properties of BzTMC(60) show clear dependence to the bond type between TM and C-60, and the eta(5)-ligand configurations tend to be in high spin states.