CHEMISTRY OF THE VANADIUM CARBON SIGMA-BOND .1. INSERTION OF CARBON-MONOXIDE, ISOCYANIDES, CARBON-DIOXIDE, AND HETEROCUMULENES INTO THE V-C BOND OF TRIS(MESITYL)VANADIUM(III)

Complex 1, [V(Mes)3(THF)], reacts with Bu(t)NC to form the homoleptic tris(eta2-iminoacyl) complex [V{eta2-C(Mes)=NBu(t)}3] (2), while the reaction with carbon monoxide leads to the elimination of MesC(O)Mes and reduction of vanadium to a vanadium-carbonyl species. Cyclohexyl and phenyl isocyanate groups insert into the three V-Mes bonds of 1, forming the tris(amido) derivatives [V{O-C(Mes)]=NCY}3], (6) and [V{0-C(Mes)-NPh}3](7). Solvated forms of 7 were prepared, giving [py-V{O-C(Mes)=NPh}3] (8) and [MeCN-V{O-C-(Mes)=NPh}3] (9). COMPlex 1 undergoes a double insertion of CyN=C=NCy (Cy = C6H11), giving [{CyN-C(Mes)-NCY}2V(Mes)] (10) which undergoes a further insertion of CO or Bu(t)-NC into the remaining V-Mes bond, forming [{CyN-C(Mes)-NCY}2V{eta2-C(Mes)+O}] (11) and [{CyN-C(Mes)-NCY}2V{eta2-C(Mes)=NBu(t)}] (12), respectively. All complexes have a high-spin d2 configuration. The structures of 1, 2, 8, and 10 have been determined by X-ray analysis. Crystallographic details: 1 is monoclinic, space group P2(1)/c, with a = 8.472(2) angstrom b = 14.273(4) angstrom c = 22.385(6) angstrom, alpha = gamma = 90-degrees, beta = 97.64(3)-degrees, Z = 4, and R = 0.057; 2 is triclinic, space group P1BAR, with a = 17.913(2) angstrom, b = 13.697(2) angstrom, c = 8.273(1) angstrom, a = 80.40(1)-degrees, beta = 80.30(1)-degrees, gamma = 88.34(l)-degrees, Z = 2, and R = 0.070; 8 is triclinic, space group P1BAR, with a = 14.701(1) angstrom, b = 14.808(l) angstrom, c = 13.267(1) angstrom, alpha = 69.06(l)-degrees, beta = 73.16(l)-degrees, gamma = 81.37(l)-degrees, Z = 2, and R = 0.062; 10 is tetragonal, space group P4(1)2(1)2, with a = 12.703(1) angstrom, b = 12.703(1) angstrom, c = 30.473(3) angstrom, alpha = beta = gamma = 90-degrees, Z = 4, and R = 0.059.