Characterization and structures of intermediates in the reactivity of CpWOs 3(CO) 11( μ3-CTol) towards dihydrogen and water

Abstract

Initial decarbonylation of CpWos 3(Co) 11( μ 3-CTol) (1: Cp = η 5-C 5 H 5, Tol = p-C 6H 4Mc) with the Me 3NO/MeCN followed by reaction with dihydrogen and water produces a dihydrido comlex CpWOs 3( CO) 10( μ 3-CTol)( μ-H) 2 (2), a ‘butterfly’ cluster with a 60 valence electron (VE), and an oxo comlex CpWOs 3(CO) 10( μ-O)( μ 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)( μ 3-CTol)( μ-H) 2 (6). Thermolysis of 2 in the presence of water gives a hydrido oxo alkylidene complex, syn-CpWOs 3(CO) 9( μ-O)( μ-CHTol)( μ-H) (3a), in which the totyl substituent on the alkylidene carbon is oriented syn to the μ-oxo ligand. Thermolysis of 4 at 110°C induces decarbonylation to give a tetrahedral alkylidyne complex CpWOs 3(CO) 9( μ-O)( μ 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 hydrido oxo alkylidene complexes, antiCpWOs 3(CO) 9( μ-O)( μ-CHToL)( μ-H) (3 b, 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 haven been isolated as crystalline solids and characterized by spectroscopic (IR, MS, 1H and 13CMMR) 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 12 12 1 with unit cell parameters a = 14.18(1), b = 28.46(1), c = 13.59(3) A ̊ , V = 5484(13) A ̊ 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) A ̊ , β = 92.83(9)°, V = 4044.0(9) A ̊ 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’ WOs 3 metal core with a respective dihedral angle of 114.3(2)° and 113.6(4)° 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 μ 3-alkylidyne caps unsymmetrically the respective WOs(2)Os(3) face of both complexes.