A series of dinuclear metallocenes with formula RMMR [R=(BCO)(5), (BNN)(5); M=Be, Mg, Ca, Zn, Cd] are investigated via density functional theory. All these compounds contain two M[eta 5-(BCO)(5)] fragments or two M[eta(5)-(BNN)(5)] fragments with a direct metal-metal single sigma bond. Detailed NBO analyses show that the metal-ligand interactions are predominantly ionic in nature and each metal atom is in its +1 oxidation state. NBO analyses indicate that the interaction between the B-B bonds and metal-metal antibond has played a role in the stabilities of these compounds.