A ligand-ligand interaction model for the structures of transition metal clusters

The model previously applied to the rationalization of simple mononuclear complexes of the type ML_n has been extended to transition metal cluster carbonyls. Application to the series of carbonyls Mn₂(CO)₁₀, Fe₂(CO)₉, Co₂(CO)₈, Fe₃(CO)₁₂, Ru₃(CO)₁₂, and the two isomers of Ir₆(CO)₁₆ reveal the importance of ligand-ligand attractive interactions and that crystal packing forces play an important role in deciding the structure adopted and, in some cases, are sufficient to cause the adopted structure to be different from that expected on the basis of intramolecular forces alone.