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 diphenylacetyle ne yield two butterfly clusters with the alkyne inserted into the tetr ametal 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 solutio n. 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 N MR spectrum. The formation of this cluster is evidently caused by bimo lecular metal-metal exchange between cluster molecules in the course o f the reaction.