Theoretical study on exohedral complexes C6H6TMB40 (TM = Sc-Ni)

Exohedral borospherene complexes comprised of 3d transition metal (TM) atoms with borospherene B-40 and benzene (C6H6) molecules, C6H6TMB40, were systematically studied by using density functional theory (DFT). Results show that in the ground states, the bonding type between TM and B-40 changes from eta(7) (TM = Sc-V) to eta(6) (TM = Cr-Fe) and then to eta(7) (TM = Co, Ni) with the increasing number of d electrons. Except for C6H6TiB40 and C6H6FeB40 being triplets, all C6H6TMB40 clusters have the lowest spin. Namely, the ground spin state with an even number of electrons is a singlet state, and the ground spin state with an odd number of electrons is a doublet state. The investigated C6H6TMB40 clusters (TM = Sc-Ni) possess higher stabilities through the ionic-covalent interactions between transition metals, benzene and the B-40 cage.