Selective Catalytic Reduction of N2 to N2H4 by a Simple Fe Complex.

The catalytic fixation of N2 by molecular Fe compounds is a rapidly developing field, yet thus far few complexes can effect this transformation, and none are selective for N2H4 production. Herein we report that the simple Fe(0) complex Fe(Et2PCH2CH2PEt2)2(N2) (1) is an efficient catalyst for the selective conversion of N2 (>25 molecules N2 fixed) into N2H4, attendant with the production of ca. one molecule of NH3. Notably, the reductant (CoCp*2) and acid (Ph2NH2OTf) used are considerably weaker than conventional chemical H+ and e- sources used in previous demonstrations of N2 turnover by synthetic Fe compounds. These results show that the direct catalytic conversion of N2 to the hydrazine oxidation state on molecular Fe complexes is viable and that the mechanism of NH3 formation by such systems may proceed via Fe-N2H4 intermediates.