COORDINATION AND TRANSFORMATIONS OF BENZOTHIENYL LIGANDS BY TRIOSMIUM CLUSTER COMPLEXES

The reactions benzothiophene and 1-bromobenzothiophene with Os-3(CO)(10)(NCMe)(2) have been investigated. The reaction of benzothiophene with Os-3(CO)(10)(NCMe)(2) at 25 degrees C yielded two pro ducts Os-3(CO)(10)(mu-SCCHC6H5)(mu-H), 1 (10%), and Os-3(CO)(9)(mu(3)-SCCC6H5)(mu-H)(2), 2 (8%). Both products were characterized by single crystal X-ray diffraction analyses. Both products contain benzothiophene ligands transformed by the activation of one and two of the C-H bonds, respectively, of the benzothiophene molecule. Compound 1 consists of a closed triosmium cluster with a mu(3)-eta(2)-benzothienyl ligand coordinated to an edge of the cluster through the C-C double bond in the five-membered ring of the ligand. Compound 2 contains a mu(3)-eta(2)-benzothiophyne ligand coordinated to the face of a closed triosmium cluster. Compound 1 was transformed to 2 in 80% yield by heating to 125 degrees C in octane solvent. The reaction of 1-bromobenzothiophene with Os-3(CO)(10)(NCMe)(2) at 25 degrees C yielded two products: Os-3(CO)(10)(mu-SCCHC6H5)(mu-Br), 3 (32%), and Os-3(CO)(9)(mu(3)-SCCHC6H5)(mu-Br), 4 (10%) Both products were characterized by single crystal X-ray diffraction analyses. Both products contain benzothienyl ligands formed by the oxidative addition of the C-Br bond of the bromobenzothiophene to the cluster. In 3 the benzothienyl ligand is coordinated across the open edge of an open triosmium cluster through the sulfur and adjacent carbon atom. In 4 the benzothienyl ligand is a triply bridging ligand using the sulfur atom and the C-C double bond of the five-membered ring. Compound 3 was transformed to 4 in 74% yield by heating to 97 degrees C in heptane solvent for 30 min. Crystal data for 1: space group = P2(1)/n, a = 7.668(2) Angstrom, b = 31.464(5) Angstrom, c = 9.452(2) Angstrom, beta = 105.48(2)degrees, Z = 4, 2563 reflections, R = 0.035. Crystal data for 2: space group = P1 $($) over bar$$, a = 9.791(1) Angstrom, b = 14.576(2) Angstrom, c = 8.094(1) Angstrom, alpha = 95.44(1)degrees, beta = 107.47(1)degrees, gamma = 95.23(1)degrees, Z = 2, 2218 reflections, R = 0.024. Crystal data for 3: space group = P2(1)/c, a = 9.116(2) Angstrom, b = 15.577(3) Angstrom c = 16.270(3) Angstrom, beta = 100.16(1)degrees, Z = 4, 2193 reflections, R = 0.038. Crystal data for 4: space group = P2(1)/n, a = 7.796(1) Angstrom, b = 15.543(3) Angstrom, c = 17.640(2) Angstrom, beta = 90.48(1)degrees, Z = 4, 2288 reflections, R = 0.028.