Synthesis and reactivity of the imidotungsten methyl cation [W(N2Npy)(NPh)Me]+: CO2 adds to the WNPh bond and does not insert into the W–Me bond

Abstract

The imidotungsten dimethyl compound [W(N₂N_py)(NPh)Me₂] 2 reacts with BAr^F₃ to form the cationic complex [W(N₂N_py)(NPh)Me]⁺ 3⁺ [anion = [MeBAr^F₃]⁻; Ar^F = C₆F₅; N₂N_py = MeC(2-C₅H₄N)(CH₂NSiMe₃)₂] which undergoes methyl group exchange with added 2, [Cp₂ZrMe₂] or ZnMe₂; treatment of cation 3⁺ with CO₂ or isocyanates leads to cycloaddition reactions at the WNPh bond and not insertion into the W–Me bond, despite the latter product being the most thermodynamically favourable according to DFT calculations.