Triggering N(2) uptake via redox-induced expulsion of coordinated NH(3) and N(2) silylation at trigonal bipyramidal iron

Abstract

The biological reduction of N-2 to give NH3 may occur by one of two predominant pathways in which nitrogenous NxHy intermediates, including hydrazine (N2H4), diazene (N2H2), nitride (N-3(-)) and imide (NH2-), may be involved. To test the validity of hypotheses on iron's direct role in the stepwise reduction of N-2, model systems for iron are needed. Such systems can test the chemical compatibility of iron with various proposed NxHy intermediates and the reactivity patterns of such species. Here we describe a trigonal bipyramidal Si(o-C6H4PR2)(3)Fe-L scaffold (R = Ph or i-Pr) in which the apical site is occupied by nitrogenous ligands such as N-2, N-2 H-4, NH3 and N2R. The system accommodates terminally bound N-2 in the three formal oxidation states (iron(0), +1 and +2). N-2 uptake is demonstrated by the displacement of its reduction partners NH3 and N2H4, and N-2 functionalizaton is illustrated by electrophilic silylation.