The B3LYP and BP86 density functional theory methods have been used to study the first row transition metal cyclopentadienylmetal carbonyls of the type Cp₂M₂(CO)_n (M = V to Ni) as well as related nitrosyl derivatives.  Structures with formal metal-metal multiple bonds are found as well as structures with four-electron donor bridging carbonyl groups and structures exhibiting spin states up to septet multiplicity.  In general unsaturated structures with metal-metal triple bonds are preferred energetically over structures with metal-metal double or quadruple bonds.