Requirements for Lewis Acid-Mediated Capture and N–N Bond Cleavage of Hydrazine at Iron

An iron complex bearing a pyridine(dicarbene) pincer was designed to probe the requirements of Lewis acid-enabled N2H4 capture and subsequent N–N bond cleavage. Appended boron Lewis acids were installed by two methods to circumvent the incompatibilities associated with Lewis acid/base quenching of free carbenes and boranes. N2H4 capture by borane Lewis acids is dependent on both the Lewis acidity and the steric profile about boron. A substitutionally inert primary coordination sphere at iron prevents an Fe–N2H4 interaction as well as N–N bond homolysis upon reduction.