A Nonheme Mononuclear {FeNO}7 Complex that Produces N2O in the Absence of an Exogenous Reductant

A new nonheme iron(II) complex, Fe-II(Me(3)TACN)((OSiPh2)(2)O) (1), is reported. Reaction of 1 with NO(g) gives a stable mononitrosyl complex Fe(NO)(Me(3)TACN)((OSiPh2)(2)O) (2), which was characterized by Mossbauer (delta=0.52 mm s(-1), |Delta E-Q|=0.80 mm s(-1)), EPR (S=3/2), resonance Raman (RR) and Fe K-edge X-ray absorption spectroscopies. The data show that 2 is an {FeNO}(7) complex with an S=3/2 spin ground state. The RR spectrum (lambda(exc)=458 nm) of 2 combined with isotopic labeling (N-15, O-18) reveals nu(N-O)=1680 cm(-1), which is highly activated, and is a nearly identical match to that seen for the reactive mononitrosyl intermediate in the nonheme iron enzyme FDPnor (nu(NO)=1681 cm(-1)). Complex 2 reacts rapidly with H2O in THF to produce the N-N coupled product N2O, providing the first example of a mononuclear nonheme iron complex that is capable of converting NO to N2O in the absence of an exogenous reductant.

Automated summary

A new nonheme iron(II) complex was reported, which reacts with NO(g) to form a stable mononitrosyl complex. The mononitrosyl complex exhibits highly activated characteristics and can rapidly convert to N2O in the absence of an exogenous reductant.