Reactivity and Mössbauer Spectroscopic Characterization of an Fe(IV) Ketimide Complex and Reinvestigation of an Fe(IV) Norbornyl Complex

Thermolysis of Fe­(NCtBu2)4 (1) for 8 h at 50 °C generates the mixed valent Fe­(III)/Fe­(II) bimetallic complex Fe2(NCtBu2)5 (2) in moderate yield. Also formed in this reaction are tert-butyl cyanide, isobutane, and isobutylene, the products of ketimide oxidation by the Fe4+ center. Reaction of 1 with 1 equiv of acetylacetone affords the Fe­(III) complex, Fe­(NCtBu2)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CtBu2)4] (5) and [Li­(THF)]2[Fe­(NCtBu2)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.