Synthesis and Characterization of an Iron(IV) Ketimide Complex

Addition of 4 equiv of LiNCtBu2 to FeCl2 in Et2O/THF results in the formation of [Li(THF)]2[Fe(NCtBu2)4] (1). Oxidation of 1 with 0.5 equiv of I2 in Et2O/DME yields [Li(DME)][Fe(NCtBu2)4] (2) in moderate yield. Both 1 and 2 are high spin and exhibit tetrahedral geometries in the solid state. Oxidation of 1 with 1 equiv of I2 in Et2O yields Fe(NCtBu2)4 (3) in good yield. Surprisingly, complex 3 exhibits a diamagnetic ground state and a nearly square planar geometry about the Fe center.