Structure and Reactivity of One- and Two-Electron Oxidized Manganese(V) Nitrido Complexes Bearing a Bulky Corrole Ligand

Abstract

As a strategy to design stable but highly reactive metal nitrido species, we have synthesized a manganese(V) nitrido complex bearing a bulky corrole ligand, [Mn^V(N)(TTPPC)]^- (1, TTPPC is the trianion of 5,10,15-Tris(2,4,6-triphenylphenyl)corrole). Complex 1 is readily oxidized by 1 equiv of Cp₂Fe⁺ to give the neutral complex 2, which can be further oxidized by 1 equiv of [(p-Br-C₆H₄)₃N^•+][B(C₆F₅)₄] to afford the cationic complex 3. All three complexes are stable in the solid state and in CH₂Cl₂ solution, and their molecular structures have been determined by X-ray crystallography. Spectroscopic and theoretical studies indicate that complexes 2 and 3 are best formulated as Mn(V) nitrido π-cation corrole [Mn^V(N)(TTPPC^+•)] and Mn(V) nitrido π-dication corrole [Mn^V(N)(TTPPC²⁺)]⁺, respectively. Complex 3 is the most reactive N atom transfer reagent among isolated nitrido complexes; it reacts with PPh₃ and styrene with second-order rate constants of 2.12 × 10⁵ and 1.95 × 10^-2 M^-1 s^-1, respectively, which are >10⁷ faster than that of 2.