INTRAMOLECULAR AND INTERMOLECULAR BONDING IN CRYSTALLINE CLUSTERS OF THE TYPE (CPR)(3)M(3)(CO)(3)[M=CO,RH,IR, CP(R)=C5H5,C(5)ME(5),C(5)H(4)ME]

The relationship between molecular and crystal structures of (Cp(R))(3 )M(3)(CO)(3) clusters [M = Co, Rh, Ir; Cp(R) = C5H5, C(5)Me(5), C(5)H( 4)Me] has been investigated by a combined use of extended Huckel molec ular orbital calculations, empirical atom-atom pairwise packing potent ial energy calculations, and computer graphics. The indenyl derivative (Ind)(3)Ir-3(mu(2)CO)(3) has also been investigated. The molecules pr esent several isomers of similar energies, and the number of bridging carbonyl groups decreases along the family cobalt, rhodium, iridium, a s the metal-metal antibonding character of the orbitals populated in c onsequence of their formation increases. Hydrogen-bonding networks of the C-H- - -O type involving the carbonyl oxygen atoms have been detec ted in all of these crystalline complexes. Facial and edge bridging CO 's are observed to form preferential interactions with respect to term inal ligands. The intermolecular and intramolecular interactions in ea ch case are discussed and compared in crystal isomers and polymorphs.