Coordination of a Complete Series of N2 Reduction Intermediates (N2H2, N2H4, and NH3) to an Iron Phosphine Scaffold

The series of dinitrogen reduction intermediates (N2H2, N2H4, and NH3) coordinated to the Fe(DMeOPrPE)(2)H+ (DMeOPrPE = 1,2-[bis(dimethoxypropyl)phosphino]ethane) scaffold has been synthesized or generated. The synthesis of trans-[Fe(DMeOPrPE)(2)(NH3)H][BPh4] and generation of trans-[Fe(DMeOPrPE)(2)(N2H4)H][BPh4] were achieved by substitution of the dinitrogen ligand on trans-[Fe(DMeOPrPE)(2)(N-2)H][BPh4]. The trans-[Fe(DMeOPrPE)(2)(N2H2)H](+) complex and its deprotonated conjugate base, trans-Fe(DMeOPrPE)(2)(N2H)H, were observed by P-31 and H-1 NMR from decomposition of trans-[Fe(DMeOPrPE)(2)(N2H4)H](+) in the presence of excess hydrazine. Attempts to chemically oxidize trans-[Fe(DMeOPrPE)(2)(N2H4)H](+) to trans-[Fe(DMeOPrPE)(2)(N2H2)H][BPh4] with a variety of oxidizing agents yielded only decomposition products consistent with the intermediate formation of trans-[Fe(DMeOPrPE)(2)(N2H2)H](+) prior to decomposition.