DARK AND PHOTOCHEMICAL-REACTIONS OF CO3RH(CO)(12) WITH DIPHENYLACETYLENE - CRYSTAL AND MOLECULAR-STRUCTURE OF THE CO3RH(MU(2)-CO)(2)(CO)(8)(MU(4),ETA(2)-PHC(2)PH) CLUSTER

Dark and photochemical reactions of Co3Rh(CO)(12) with diphenylacetylene yield two butterfly clusters with the alkyne inserted into the tetrametal framework. One of them is the previously unknown cluster Co3Rh(mu - CO)(2)(CO)(8)(mu(4),eta(2) - PhC(2)Ph). It was characterized by X-ray crystallography (dark violet compound crystallizing in monoclinic space group C2/c, a = 15.665(2), b = 17.947(5), c = 9.078(1) Angstrom, beta = 93.91(1)degrees, v = 2546.1(8) Angstrom(3), Z = 4). The C-13 NMR study showed that the solid state structure is retained in solution. The second product is the Co2Rh2(mu - CO)(2)(CO)(8)(mu(4),eta(2) - PhC(2)Ph) cluster obtained earlier and identified herein by its C-13 NMR spectrum. The formation of this cluster is evidently caused by bimolecular metal-metal exchange between cluster molecules in the course of the reaction.