Sulfur-Bridged Ta–M (M = Mo, Cr) Multinuclear Complexes Bearing a Four-Electron-Reduced Dinitrogen Ligand

Sulfur-bridged Ta₂M₂ complexes (M = Mo, Cr) containing a four-electron-reduced dinitrogen ligand, [Cp*Ta(μ-SC₆H₄Me)₂M(CO)₄]₂(μ-η¹:η¹-N₂) (Cp* = η⁵-C₅Me₅), were synthesized from the ditantalum complex [Cp*Ta(SC₆H₄Me)₂]₂(μ-η¹:η¹-N₂), which was obtained by a one-pot reaction using [Cp*TaCl₄], di-p-tolyl disulfide, and KC₈ under dinitrogen. Crystal structures of the Ta₂ and Ta₂M₂ complexes revealed the analogy of the Ta–N–N–Ta moieties. This new route demonstrates the stability of the N₂^4– ligand in M–S bond formation reactions, which are applicable to the synthesis of sulfur-bridged complexes bearing reduced dinitrogen species.