SYNTHESES, STRUCTURES, AND REACTIVITY OF A SERIES OF (PENTAMETHYLCYCLOPENTADIENYL)MOLYBDENUM(V) AND (PENTAMETHYLCYCLOPENTADIENYL)TUNGSTEN(V) IMIDO COMPLEXES

Reactions of the (pentamethylcyclopentadienyl)molybdenum(V) and -tungs ten(V) tetrachlorides (eta(5)-C(5)Me(5))MCl(4) (M = Mo, W) with the pr imary amines RNH(2) (R = t-Bu, i-Pr, C6F5, and 2,6-(i-Pr)(2)C6H3) lead to the formation of the imido complexes [(eta(5)-C(5)Me(5))M(NR)Cl-2] (3a-h). X-ray structure analyses of 3a, 3c, and 3e reveal their monom eric nature. 3e and 3e crystallize in the monoclinic space group P2(1) /c with the lattice parameters a = 15.171(3) Angstrom, b = 7.615(2) An gstrom, c = 14.758(3) Angstrom, beta = 90.29(3)degrees, and V = 1704.9 (7) Angstrom(3) for 3e and a = 10.4502(7) Angstrom, b = 10.6897(8) Ang strom, c = 15.915(2) Angstrom, beta = 94.342(8)degrees, and V = 1772.7 (3) Angstrom(3) for 3c. 3a crystallizes in the orthorhombic space grou p P2(1)2(1)2(1) with a = 8.6040(10) Angstrom, b = 12.0490(10) Angstrom , c = 17.020(2) Angstrom, and V = 1764.5(3) Angstrom(3). The metal-nit rogen distances of these 17-electron complexes (1.719(3) Angstrom, for 3a, 1.716(12) Angstrom for 3e, and 1.748(2) Angstrom for 3c) correspo nd to a triple bond. (eta(5)-C(5)Me(5))W(NC6F5)Cl-2 (3g) decomposes in the presence of air to the half-sandwich tungsten(VI) imido complex ( eta(5)-C(5)Me(5))W(NC6F5)Cl-3 (4) and a green solid. Further hydrolysi s of 3g results in the dinuclear tungsten(VI) oxo complex [(eta(5)-C(5 )Me(5))WO2](2)(mu-O)C6F5NH2 (5) with a linear W-O-W bridge. The comple xes have been characterized by X-ray diffraction. 4 crystallizes in th e triclinic space group <P(1)over bar>, with a = 7.3843(1) Angstrom, b = 11.529(2) Angstrom, c = 11.558(2) Angstrom, alpha = 77.38(2)degrees , beta = 80.15(2)degrees, gamma = 79.88(2)degrees and V = 936.2(3) Ang strom(3); 5 crystallizes in the monoclinic space group P2(1)/n, with a = 1.3246(3) Angstrom b = 1.0042(3) Angstrom, c = 1.4102(3) Angstrom, beta = 104.37(3)degrees, and V = 1.8173(6) Angstrom(3).