Organometallic Chemistry of Vanadium(III) Based on the Vanadium-Dibenzotetramethyltetraaza[14]annulene Moiety: Synthesis, Structural Studies by X-Ray and 1H NMR Spectroscopy, and Reactivity of Vanadium-Carbon Functionalities

Reaction of VC13(THF)3 with tmtaaLi2 gave the monochloro derivative [(tmtaa)V(Cl)] (1). It was converted by conventional methods into the corresponding alkyl and aryl derivatives [(tmtaa)V(R)] [R = Me (2), CH2Ph (3), Ph (4), 2, 4, 6-Me3C6H2 = Mes (5)]. A nonconventional synthetic route leading to the [(tmtaa)V133] organometallic derivatives uses [(tmtaa)V(O)] (6) as starting material. The structures of 1, 4, and 5 have been determined by an X-ray analysis. In addition, they have been inspected in solution, though they are paramagnetic, by H NMR spectroscopy. The V-R bond does not behave normally in the reaction with carbon monoxide. Such a reaction led to the deoxygenation of the acyl or ketone intermediate, forming 6. An indirect proof of the occurrence of the insertion reaction into a V-C bond was obtained in the reaction of 3 with C6HnNC, leading to [(tmtaa)V-C(NC6Hn)CH2Ph] (13). Crystallographic details are as follows: 1, space group P21/n, monoclinic, a = 8.558 (2) X, b = 20.451 (5) Â, c = 13.514 (3) Â, α = γ = 90°, β = 93.06 (2)°, Z = 4, and R = 0.072 for 1327 independent observed reflections; 4, space group Pi, triclinic, a = 9.597 (2) X, b = 10.635 (2) Â, c = 12.296 (2) Â, α = 82.48 (2)°, β = 68.14 (1)°, 7 = 80.07 (1)°, Z = 2, and R = 0.042 for 2151 independent observed reflections; 5, space group Pi, triclinic, a = 12.671 (4) Â, b = 13.501 (5) k, c= 14.613 (4) Å α = 113.58 (3)°, β = 93.80 (3)°, γ = 109.79 (3)°, Z = 2, and R = 0.075 for 3116 independent observed reflections.