Syntheses, crystal structures and properties of four iron and cobalt complexes bearing 1,3,5-triazapentadienyl ligands

Addition reactions of MN(R)SiMe3 (R = Ph or SiMe3, M = Li or Na) to 2 equivalents of α-hydrogen-free 1-piperidinecarbonitrile generated [M{N(R)C(R′)NC(R′)N(SiMe3)}]2 [(1a), R = SiMe3, R′ = 1-piperidino, M = Li; (1b), R = Ph, R′ = 1-piperidino, M = Li; (1c), R = Ph, R′ = 1-piperidino, M = Na] which further reacted with MCl2 (M = Fe, Co) to give M[{N(SiMe3)C(R′)}2N]2 [R′ = 1-piperidino, M = Fe (2); Co (3)] and M[N(Ph)C(R′)NC(R′)N(SiMe3)]2 [R′ = 1-piperidino, M = Fe (4); Co (5)], respectively. In each of the crystalline complexes 2–5 the MNCNCN rings are planar. The Fe and Co centers in 2–5 feature a tetrahedral environment in N, N′-1,5-chelated fashion. The molecular structures of 2–5 are presented. Furthermore, the thermal properties of the four complexes have been investigated.

Four iron and cobalt complexes bearing 1,3,5-triazapentadienyl ligands have been synthesized from insertion reactions of the amido ligands into the –CN functionality, followed by 1,3-silyl migrations. These six-electron monoanionic ligands are bound to the metal center in N,N′-1,5-chelated fashion as good σ- and π-donors.Figure optionsDownload as PowerPoint slide