Reactivity and Mössbauer spectroscopic characterization of an Fe(IV) ketimide complex and reinvestigation of an Fe(IV) norbornyl complex.

Thermolysis of Fe(N═C(t)Bu2)4 (1) for 8 h at 50 °C generates the mixed valent Fe(III)/Fe(II) bimetallic complex Fe2(N═C(t)Bu2)5 (2) in moderate yield. Also formed in this reaction are tert-butyl cyanide, isobutane, and isobutylene, the products of ketimide oxidation by the Fe(4+) center. Reaction of 1 with 1 equiv of acetylacetone affords the Fe(III) complex, Fe(N═C(t)Bu2)2(acac) (3), concomitant with formation of bis(tert-butyl)ketimine, tert-butyl cyanide, isobutane, and isobutylene. In addition, the Mössbauer spectra of 1 and its lower-valent analogues [Li(12-crown-4)2][Fe(N═C(t)Bu2)4] (5) and [Li(THF)]2[Fe(N═C(t)Bu2)4] (6) were recorded. We also revisited the chemistry of Fe(1-norbornyl)4 (4) to elucidate its solid-state molecular structure and determine its Mössbauer spectrum, for comparison with that recorded for 1.