NUCLEOPHILIC RING-OPENING OF A BRIDGING THIETANE LIGAND IN AN OPEN TETRAOSMIUM CARBONYL CLUSTER COMPLEX

The complex Os4(CO)12(mu-CO)[mu-SCH2CMe2CH2] (1) Was found to react with bis(triphenylphosphine)nitrogen(1+) chloride, [PPN]Cl, at 25-degrees-C to yield the salt [PPN][Os4(mu-CO)(CO)12(mu-SCH2CMe2CH2Cl) (2; 43%), in which the chloride ion was added to one of the methylene groups of the SCH2CMe2CH2 ligand in a ring-opening process that involved the cleavage of one of the carbon-sulfur bonds Compound 2 was converted to the neutral complex Os4(CO)13(mu-SCH2CMe2CH2Cl)(mu-H) (3) by protonation with HCI. Complex 3 was characterized crystallographically and was found to contain a 4-chloro-3,3-dimethylpropanethiolato ligand bridging the wing-tip metal atoms of a butterfly tetrahedron of four metal atoms in the cluster. A hydride ligand bridges one of the edge metal-metal bonds of the cluster. Compound 3 was obtained in good yield (67%) in one step by the reaction of 1 with HCL At 97-degrees-C, 3 was decarbonylated to form the complex Os4(CO)12(mu-3SCH2CMe2CH2Cl)(mu-H) (4; 97%). Compound 4 was also characterized crystallographically and was found to contain a triply bridging 4-chloro-3,3-dimethylpropanethiolato ligand serving as a 5-electron donor. Data for 1: space group = P1BAR, a = 10.205 (4) angstrom, b = 14.399 (2) angstrom, c = 9.342 (2) angstrom, alpha = 92.52 (2)-degrees, beta = 108.89 (3)-degrees, gamma = 85.82 (2)-degrees, Z = 2,2678 reflections, R = 0.029. Data for 3: space group = P1BAR, a = 20.646 (4) angstrom, b = 9.610 (1) angstrom, c = 8.753 (1) angstrom, alpha = 116.308 (9)-degrees, beta = 102.27 (2)-degrees, gamma = 75.12 (1)-degrees, Z = 2, 3186 reflections, R = 0.032. Data for 4: space group = P1BAR, a = 10.558 (1) angstrom, b = 13.673 (2) angstrom, c = 9.473 (1) angstrom, alpha = 94.10 (1)-degrees, beta = 91.424 (9)-degrees, gamma = 76.08 (1)-degrees, Z = 2, 2421 reflections, R = 0.036.