MOLECULAR-ORBITAL CALCULATIONS ON FE4(CO)10(MU-CO)(MU-4-SE)2 AND FE3RU(CO)10(MU-CO)(MU-4-SE)2

Molecular orbital calculations using the extended Huckel program were carried out on Fe4(CO)10(mu-CO)(mu4-Se)2 and Fe3Ru(CO)10(mu-CO)(mu4-Se )2. On the basis of a molecular orbital description, binding energy, p olarity and the metal-metal bond order were found to decrease on subst itution of one Fe atom of Fe4(CO)10(mu-CO)(mu4-Se)2 by a Ru atom.