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

Exohedral borospherene complexes comprised of 3d transition metal (TM) atoms with borospherene B40 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 B40 changes from η7 (TM = Sc-V) to η6 (TM = Cr-Fe) and then to η7 (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 B40 cage.