Preference for trihapto/monohapto over bis(dihapto) metal-ligand bonding in binuclear hexafluorocyclopentadiene cobalt carbonyls

All three low-energy structures of (C5F6)Co2(CO)8 have the hexafluorocyclopentadiene ligand bonded to two Co(CO)4 units as monohapto ligands leaving an uncomplexed CC double bond. The lowest energy (C5F6)Co2(CO)n (n = 7, 6, 5, 4) structures all have the hexafluorocyclopentadiene ligand bonded to one cobalt atom as a trihapto ligand and to the other cobalt atom as a monohapto ligand. Cobalt-cobalt bonds are found in the unsaturated (C5F6)Co2(CO)n (n = 6, 5, 4) systems.