SYNTHESIS AND MOLECULAR-STRUCTURE OF A MOLYBDENUM DIFLUOROCARBENE COMPLEX, [(ETA-5-C5ME5)MO(CO)3(CF2)]OSO2CF3

Treatment of (eta-5-C5R5)Mo(CO)3CF3 (R = H, Me (3)) with Me3SiOTf in benzene solution at ambient temperature results in precipitation of the corresponding carbene triflate salts [(eta-5-C5H5)Mo(CO)3(CF2)]OTf (1) and [(eta-5-C5Me5)Mo(CO)3(CF2)]OTf (4) in high yield. The solid-state structures of 4 and its trifluoromethyl precursor 3 have been determined. In addition to being the first example of a structurally characterized group VI dihalocarbene complex, the observed lateral orientation of the planar CF2 carbene moiety with respect to the basal plane in 4 is unprecedented for CpML3(carbene) systems. Crystal data for 3: orthorhombic, P21cn, with a = 9.208 (1) angstrom, b = 9.822 (1) angstrom, c = 17.176 (2) angstrom, V = 1553.4 (3) angstrom 3, Z = 4, R(F) = 2.49%, and R(wF) = 3.52%. Crystal data for 4: tetragonal, P4(2)/mbc, with a = 17.895 (2) angstrom, c = 12.040 (2) angstrom, V = 3855.5 (10) angstrom 3, Z = 8, R(F) = 3.86%, and R(wF) = 3.78%.