Characterization and structures of intermediates in the reactivity of CpWOs(3)(CO)(11)(mu(3)-CTol) towards dihydrogen and water

Abstract

Initial decarbonylation of CpWOs(3)(CO)(11)(mu(3)-CTol) (1; Cp = eta(5)-C5H5, Tol = p-C(6)H(4)Me) with Me(3)NO/MeCN followed by reaction with dihydrogen and water produces a dihydrido complex CpWOs(3)(CO)(10)(mu(3)-CTol)(mu-H)(2) (2), a 'butterfly' cluster with a 60 valence electron (VE), and an oxo complex CpWOs(3)(CO)(10)(mu-O)(mu(3)-CTol) (4) respectively. Complex 2 reacts either with carbon monoxide to produce the starting alkylidyne complex 1 by reductive elimination of dihydrogen or with PPh(3) to afford a 62 VE 'butterfly' complex CpWOs(3)(CO)(10)(PPh(3))(mu(3)-CTol)(mu-H)(2) (6). Thermolysis of 2 in the presence of water gives a hydride oxo alkylidene complex, syn-CpWOs(3)(CO)(9)(mu-O)(mu-CHTol)(mu-H) (3a), in which the tolyl substituent on the alkylidene carbon is oriented syn to the mu-oxo ligand, Thermolysis of 4 at 110 degrees C induces decarbonylation to give a tetrahedral alkylidyne complex CpWOs(3)(CO)(9)(mu-O)(mu(3)-CTol) (5), which is reversibly converted back to 4 upon exposure to carbon monoxide. Complex 5 reacts with dihydrogen to afford a mixture of two isomeric hydride oxo alkylidene complexes, anti-CpWOs(3)(CO)(9)(mu-O)(mu-CHTol)(mu-H) (3b,c). The syn-isomer 3a is also produced from a mixture of 3b and 3c by thermolysis in boiling toluene. Compounds 2, 3a,b,c, 4, 5 and 6 have been isolated as crystalline solids and characterized by spectroscopic (IR, MS, H-1 and C-13 NMR) and analytical data. The structures of 2 and 6 have been determined by single crystal X-ray diffraction studies. Compound 2 crystallizes in the orthorhombic space group P2(1)2(1)2(1) with unit cell parameters a = 14.18(1), b = 28.46(1), c = 13.59(3) Angstrom, V = 5484(13)Angstrom(3) and Z = 8. Compound 6 crystallizes in the monoclinic space group P2(1)/n with unit cell parameters a = 19.298(2), b = 22.406(4), c = 9.364(1)Angstrom, beta = 92.83(9)degrees, V = 4044.0(9)Angstrom(3) and Z = 4. Diffraction data were collected on a CAD4 diffractometer, and structures were refined to R = 0.0957 and 0.0510 for 2 and 6 respectively. Both 2 and 6 are based upon a 'butterfly' WOs3 metal core with a respective dihedral angle of 114.3(2)degrees and 113.6(4)degrees between the W-Os(2)-Os(1) and W-Os(2)-Os(3) planes. Each molecule consists of three Os(CO)(3) units and a CpW(CO) fragment, except that the Os(1) center in 6 is additionally coordinated with PPh(3). The mu(3)-alkylidyne caps unsymmetrically the respective W-Os(2)-Os(3) face of both complexes.