Reductive N–N bond cleavage and coupling of organic azides mediated by chromium(i) and vanadium(i) β-diketiminate

Abstract

Reactions of organic azides RN₃ with two univalent inverted-sandwich complexes (μ-η⁶:η⁶-C₆H₅CH₃)[M(Nacnac)]₂ (M = Cr (1) and V (2); Nacnac = HC(C(Me)NC₆H₃ⁱPr₂)₂) have been investigated. Where R = p-tolyl, reaction with 1 results in reductive N₂ elimination and the formation of a diimido product Cr(NR)₂(Nacnac) and a cycloaddition tetrazene product Cr[N(R)NNN(R)](Nacnac), which can be converted to Cr(NR)₂(Nacnac) upon thermolysis. However, reaction of 1 with Me₃SiN₃ does not produce a diimido complex, but a monomeric three-coordinate amido product Cr[N(SiMe₃)₂](Nacnac) and an azide-bridged dinuclear compound [Cr(μ-N₃)(Nacnac)]₂. On the other hand, where R = p-tolyl, 1-adamantyl, or SiMe₃, reaction with the more reducing 2 gives solely a diimido product V(NR)₂(Nacnac). The symmetric diimido complex V(NSiMe₃)₂(Nacnac) (10) can be converted to an asymmetric diimido complex V(NSiMe₃)(N-2,6-C₆H₃ⁱPr₂)[Me₃SiNC(Me)C(H)C(Me)N(2,6-C₆H₃ⁱPr₂)] (11) upon heating.