CLUSTER COMPLEXES CONTAINING POLYENE LIGANDS - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF 2 ISOMERS OF RU6(CO)14(MU-6-C)(TRANS-1,3,5-CH2CHCHCHCHCH2) CONTAINING TRANS-1,3,5-HEXATRIENE LIGANDS

Two carbidohexaruthenium carbonyl cluster complexes, Ru6(CO) 14(mu6-C)(mu-S-cis,s-cis-trans-1,2-eta2-4-6-eta4-CH2CHCHCHCHCH2), 2a, (3%), and Ru6(CO)14(mu6-C)(mu-s-trans,s-cis-trans-1,2-eta2-4-6-eta4-CH2CHCHCHCHCH2), 2b (19%), containing trans-1,3,5-hexatriene ligands in different conformations and the known compound RU6(CO)14(mu6-C)(eta6-C6H6), 3 (22%), were obtained from the reaction of Ru6(CO)17(mu6-C) with 1,3,5-hexatriene (a mixture of cis- and trans-isomers) at 155-degrees-C. Compounds 2a and 2b were characterized by IR, H-1 NMR, and single-crystal X-ray diffraction analyses. The structures of both 2a and 2b contain an octahedral cluster of six ruthenium atoms with the carbide ligand located in the center and a bridging trans-eta6-hexatriene ligand. The difference between 2a and 2b lies in the conformations of the hexatriene ligand. In 2a, it adopts an s-cis,s-cis conformation while, in 2b, it exhibits an s-trans,s-cis mode. Crystal data for 2a: space group P2(1)/n, a = 14.794(2) angstrom, b = 12.290(2) angstrom, c = 14.927(3) angstrom, beta = 92.95(l)-degrees, R = 0.033 for 2078 reflections. For 2b: space group P2(1)/n, a = 14.812 (2) angstrom, b = 12.202(2) angstrom, c = 14.866(2) angstrom, beta = 92.06(l)-degrees, R = 0.027 for 2608 reflections.