Figure 1. Synthetic scheme for the generation of Fe-N2+, Fe-N2, and Fe-N2- (3, 4b, 5 and 5’).

Exposure of ammonia to cationic Fe-THF+ (2a, R = Ph or 3, R = iPr) affords the ammonia complexes 7a and 7b. Upon addition of Cp*2Cr nitrogen uptake generates Fe-N2 (4a or 4b) with quantitative release of NH3. Sodium naphthalide reduction of 4b generates Fe-N2- (5 and 5’).