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

Thermolysis of Fe(N=(CBu2)-Bu-t)(4) (1) for 8 h at 50 degrees C generates the mixed valent Fe(III)/Fe(II) bimetallic complex Fe-2(N=(CBu2)-Bu-t)(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=(CBu2)-Bu-t)(2)(acac) (3), concomitant with formation of bis(tert-butyl)ketimine, tert-butyl cyanide, isobutane, and isobutylene. In addition, the Mossbauer spectra of 1 and its lower-valent analogues [Li(12-crown-4)(2)][Fe(N=(CBu2)-Bu-t)(4)] (5) and [Li(THF)](2)[Fe(N=(CBu2)-Bu-t)(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 Mossbauer spectrum, for comparison with that recorded for 1.