CYCLOBUTYNE LIGANDS .4. RUTHENIUM CARBONYL CLUSTERS CONTAINING SUBSTITUTED CYCLOBUTYNE LIGANDS AND THE 1ST EXAMPLE OF A QUADRUPLY BRIDGING CYCLOBUTYNE LIGAND

The reaction of 4-tert-butyl-4-methyl-1-(phenylthio)cyclobutene with Ru3(CO)12 at 98-degrees-C has yielded four new complexes: Ru4(CO)12[mu4-SC2CH2C(Me)(t)Bu] (1, 12%), {Ru3(CO)8[mu3-eta2-C2CH2C(Me)(t)Bu](mu4-S)}2 (2; 1%), Ru4(CO)11[mu4-eta2-C2CH2C(Me)(t)Bu](mu4-S) (3; 14%), and a trace of Ru6(CO)16[mu4-CCHCH=C(Me)(t)Bu](mu4-S)(4; 1%). All four products were characterized by single-crystal X-ray diffraction analyses. Compounds 2 and 3 contain new examples of the disubstituted cyclobutyne ligand C2CH2C(Me)(t)Bu, formed by the cleavage of the hydrogen atom and the phenylthio group from the cyclobutene ring. Compound 1 contains a quadruply bridging metalated 1-sulfidocyclobutenyl group. It was transformed to compound 3, which contains the first example of a quadruply bridging cyclobutyne ligand. Compound 4 contains six ruthenium atoms arranged in the shape of an edge-bridged square-pyramidal cluster. A sulfido ligand bridges the square base, and a CH-C(Me)(t)Bu substituted-vinylidene ligand bridges one triangle of the square pyramid and the edge-bridging ruthenium atom. Compound 2 is a dimer that can be split by reaction with CO to yield two of the monomeric triruthenium cluster complexes Ru3(CO)9[mu3-eta2-C2CH2C(Me)(t)Bu](mu3-S)(5). When heated to 68-degrees-C, compound 5 is decarbonylated and converted back into 2. Compound 5 was also characterized crystallographically. Crystal data for 1: space group P2(1)/c, a = 10.014(2) angstrom, b = 11.662(2) angstrom, c = 23.642(3) angstrom, beta = 92.48(1)degrees, Z = 4, 2589 reflections, R = 0.027. Crystal data for 2.C6H6: space group P2(1)/c, a = 18.793(3) angstrom, b = 15.109(3) angstrom, c = 19.039(4) angstrom, beta = 114.89(2)degrees, Z = 4, 3180 reflections, R = 0.033. Crystal data for 3: space group P1BAR, a = 10.429(1) angstrom, b = 11.566(2) angstrom, c = 10.893(1) angstrom, alpha = 89.94(1)degrees, beta = 98.308(8)degrees, gamma = 90.36(1)degrees, Z = 2, 2871 reflections, R = 0.025. Crystal data for 4: space group P2(1)/c, a = 16.395(2) angstrom, b = 12.117(3) angstrom, c = 18.382(3) angstrom, beta = 107.01(1)degrees, Z = 4,2741 reflections, R=0.032. Crystal data for 5: space group P2(1)/c, a = 9.138(2) angstrom, b = 17.845(3) angstrom, c = 14.415(2) angstrom, beta = 93.29(1)degrees, Z = 4, 2152 reflections, R = 0.021.