THERMAL CHEMISTRY OF CPMO(NO)(CH2CME3)2 - LEWIS BASE ADDUCTS OF CPMO(NO)(=CHCME3) AND A NEW BONDING MODE FOR NITRIC-OXIDE

Treatment of CpMo(NO)Cl2 with (Me3CCX2)2Mg-X(dioxane) [X = H, D] in TH F at low temperatures provides moderate yields of the bis(neopentyl) c omplexes, CpMo(NO)(CH2CMe3)2 (1) and CpMo(NO)(CD2CMe3)2 (1-d4). The so lid-state molecular structure of 1-d4 has been determined at 170 K. Cr ystals of 1-d4 are monoclinic of space group P2(1)/n; a = 5.9781(6) an gstrom, b = 20.065(4) angstrom, c = 13.6355(17) angstrom; beta = 95.52 (1)-degrees; Z = 4; R = 0.025, R(w) = 0.032 for 2494 reflections with I greater-than-or-equal-to 2.5sigma(I). Room-temperature thermolysis o f 1 in CH2Cl2 solution provides bimetallic [CpMo(NO)](mu-eta1:eta2-NO) (mu-CHCMe3) [CPMo[=CHCMe3)] (2) in which the unprecedented mu2-eta1:et a2-NO ligand formally provides five electrons to the two Mo centers. C rystals of 2 are orthorhombic of space group Pcab: a = 17.836(2) angst rom, b = 18.265(2) angstrom, c = 13.198(2) angstrom; Z = 8; R = 0.042, R(w) = 0.037 for 4081 reflections with I greater-than-or-equal-to 3si gma(I). Thermolysis of 1 in the presence of phosphines or pyridine (L) provides the monomeric adducts, CpMo(NO)(=CHCMe3)(L) (3-5, 7) of whic h CpMo(NO)(=CHCMe3)(PPh2Me) (3) has been crystallographically characte rized. Crystals of 3 are monoclinic of space group P2(1)/n: a = 9.328( 2) angstrom, b = 15.516(3) angstrom, c = 15.188(2) angstrom, beta = 93 .72(1)-degrees; Z = 4; R = 0.027, R(w) = 0.026 for 3406 reflections wi th I greater-than-or-equal-to 3sigma(I). Thermolysis of 1 in the prese nce of excess PMe3 in CH2Cl2 affords [(Me3P)4Mo(NO)Cl]2 (6). Displacem ent of pyridine (py) from CpMo(NO)(=CHCMe3)(PY) (7) with a stoichiomet ric amount of PMe3 produces CpMo(NO)(=CHCMe3)(PMe3)(8). Reaction of 1 with CNCMe3 yields the eta2-iminoacyl complex, CpMo(NO)(eta2-C{NCMe3}C H2CMe3)(CH2CMe3) (9).