How are the energetically extremely unfavorable intermediates in nitrogenase reduction of N2 stabilized? By complexation, steric hindrance, and strong hydrogen bonding! At least this is the answer suggested by the complex 1. Diazene (HN NH) is stabilized in 1 by bonding to Fe centers that are completely surrounded by biologically relevant donor atoms. Thus, 1 is a model complex for enzymatic nitrogen fixation in both a functional and a structural sense.