Imido complexes of the late transition metals are involved in several catalytic group-transfer reactions, including aziridination and amination. In addition, imidoiron complexes (Fe=NR) are isoelectronic with the oxoiron complexes (Fe=O) utilized as intermediates in biological oxidation reactions. Despite the potential for intermediacy of imidoiron complexes in catalytic reactions, previously isolated iron complexes with terminal imido ligands are generally not catalytically active. This presentation describes spectroscopic characterization of an intermediate spin (S = 3/2) imidoiron(III) complex as well as several examples of nitrene group-transfer, including catalytic formation of asymmetric carbodiimides. Kinetic data addressing the mechanism of the catalytic reaction will be discussed.