Chemistry of the Vanadium-Carbon sigma Bond. 3. The Reactivity of a Homoleptic Tris(eta2-iminoacyl) Complex of Vanadium(III)

The chemistry of the homoleptic tris(iminoacyl)vanadium(III) compound [V{(η2-C(Mes) NBut}3] (1) has been explored in the following ways, (i) Reactions with CO2 analogues: the reaction with CO2 led to a double insertion of CO2 into the VC bond with the formation of [V{η2-C(Mes)NBut}{ButNC(Mes)C(0)0}2] (2), containing an α-imino acid anion as ligand. An α-imino amide complex was obtained from the reaction of 1 with CyNCO (Cy  C6H11), leading to [V{η2-C(Mes)NBut}2{ButNC(Mes)C(O)NC6H11}] (3). (ii) Reactions with carbon monoxide and isocyanides: the reaction with CO leads to the isolation of the unusual monocarbonyl adduct [V{η2-C(Mes)NBut}3(CO)] (4), which is diamagnetic and has a CO band at 1867 cm−1. The reaction with Ph2CN2 was facilitated by the electron richness of 1 and gave the diamagnetic adduct [V{η2-C(Mes)NBut}3(η2-Ph2CNN)] (5). The reaction of 1 with ButNC is more complex and led to a V(IV) metallacycle, [V{η2-C(Mes)NBut}2-{ButNC(Mes)C(CN)NBut}] (6), via a one-electron oxidation of vanadium, (iii) Reaction with hydrogen: complex 1 reacts with H2 at −30 °C in the absence of catalyst to give, by hydrogenation of iminoacyl groups, [V{η2-C(Mes)NBut}2(ButN-CH2Ph)] (9) and [V{η2-C-(Mes)NBut}(ButNCH2Ph)2] (10). Complex 10 decomposes at room temperature, leading to a dimeric diamagnetic V(IV) complex containing a single metalmetal bond, 17. (iv) Oxidation of 1 by CCl, PCl, and SS bonds: reaction of 1 with PhCH2Cl, PhCOCl, and Ph2PCl led to the formation of the corresponding V(IV) derivative [V{η2-C(Mes)NBut}3(Cl)] (18), while the reaction with PhSSPhgave [V{η2-C(Mes)NBut}3(SPh)] (19). Crystallographic details: 2 is triclinic, space group P1̄, with a = 11.253(1) Å, b = 22.818(2) Å, c = 8.538(1) Å, α = 93.85(1)°, β = 94.58(1)°, γ = 100.95(1)°, Z = 2, and R = 0.056; 3 is monoclinic, space group P21/n, with a = 24.420(2) Å, b = 15.902(1) Å, c = 12.089(1) Å, α = γ = 90°, β = 104.00(1)°, Z = 4, and R = 0.056; 6 is monoclinic, space group P21/n, with a = 20.440(2) Å, b = 21.143(2) Å, c = 11.647(1) Å, α = γ = 90°, β = 97.15(1)°, Z = 4, and R = 0.060; 17 is monoclinic, space group P21/c, with a = 10.049(1) Å, b = 20.675(2) Å, c = 18.107(2) Å, α = γ = 90°, β = 102.30(1)°, Z = 4, and R = 0.043; 18 is monoclinic, space group P21/n, with a = 14.656(1) Å, b = 24.710(1) Å, c = 11.112(1) Å, α = γ = 90°, β = 90.39(1)°, Z = 4, and R = 0.051; 19 is orthorhombic, space group Pbca, with a = 36.456(3) Å, b = 12.411(1) Å, c = 19.943(1) Å, α = β = γ = 90°, Z = 4, and R = 0.058.