FORMATION OF BUTENETHIOLATE BY THE RING-OPENING OF TETRAHYDROTHIOPHENE BY A TRIOSMIUM CLUSTER COMPLEX

The complex OS3(CO)10(SCH2CH2CH2CH2)2 (1) was prepared by the reaction of Os3(CO)10(NCMe)2 with tetrahydrothiophene (THT) at 25-degrees-C. When heated to 97-degrees-C, 1 was transformed into the complex OS3(CO)10[mu-eta2-(SCH2CH2Ch2CH)](mu-H) (2) by loss of one THT ligand and the activation of a C-H bond on one of the methylene groups bonded to the sulfur atom. At 125-degrees-C, 2 was decarbonylated and transformed into the new compound Os3(CO)9[mu-eta3-S(CH2)2CH=CH2](mu-H) (3) by a ring-opening cleavage of one of the C-S bonds. Compound 3 contains a 3-butenethiolate ligand in which the sulfur atom bridges one of the metal-metal bonds and the double bond is pi-coordinated to one of the sulfur-bridged metal atoms. An investigation of the transformation of Os3(CO)10[mu-(SCH2CD2CD2CH)]-(mu-H) (2-d4) into Os3(CO)9[mu-eta3-SCH2CD2CD=CH2](mu-D) (3-d4) at 125-degrees-C showed that the hydride ligand was returned to the carbon atom from which it was initially cleaved and deuterium was shifted to the metal atoms. When heated to 205-degrees-C, compound 3 released butene. Complexes 1-3 were characterized by single-crystal X-ray diffraction analysis. Crystallographic data: for 1, space group P1BAR, a = 12.412(4) angstrom, b = 12.658(2) angstrom, c = 9.355(2) angstrom, alpha = 108.86(2)degrees, beta = 112.04(3)degrees, gamma = 96.18(2)degrees, Z = 2,2681 reflections, R = 0.029; for 2, space group P2(1)/a,a = 12.975(2) angstrom, b = 21.679(8) angstrom, c = 21.865(4) angstrom, beta = 100.87(1)degrees, Z = 12, 4129 reflections, R = 0.047; for 3, space group Pbca, a = 16.556(4) angstrom, b = 18.452(3) angstrom, c = 12.490(3) angstrom, z = 8, 1693 reflections, R = 0.048.