Dinitrogen functionalization at a ditantalum center. Balancing N2 displacement and N2 functionalization in the reaction of coordinated N2 with CS2

Abstract

The reaction of carbon disulfide (CS₂) with the side-on end-on dinitrogen complex ([NPN^Si]Ta)₂(μ–η¹:η²-N₂)(μ-H)₂ (1) (where [NPN^Si] = [PhP(CH₂SiMe₂NPh)₂]) has been studied and shown to generate two products, the ratio of which depends on the concentration of added carbon disulfide. At high concentrations of CS₂, N–N bond cleavage and functionalization occur to generate a ditantalum complex with an isothiocyanato ligand N-bound to Ta along with bridging sulfido and nitrido moieties. At lower concentrations of CS₂, less dinitrogen functionalization is observed; instead, N₂ is displaced and the CS₂ molecule is completely disassembled to generate a ditantalum derivative with bridging methylene and two sulfide moieties. Kinetic and DFT studies have been performed and provide clues about the product ratio and mechanistic information and shed light on why N₂ functionalization is challenging.