A Low-Spin d⁵ Iron Imide: Nitrene Capture by Low-Coordinate Iron(I) Provides the 4-Coordinate Fe(III) Complex [PhB(CH₂PPh₂)₃]Fe⋮N-<i>p</i>-tolyl

Abstract

Entry into "[PhBP3]Fe" chemistry affords a rare, pseudotetrahedral iron(I) complex, [PhBP3]Fe(PPh3), with an S = 3/2 ground state. This precursor undergoes rapid oxidation by aryl azide to produce the d5 imide [PhBP3]FeNAr (Ar = p-tolyl). The Fe(III) imide is significant in that it is low-spin and represents the first mononuclear imide of iron. Doublet [PhBP3]FeNAr reacts rapidly and quantitatively with CO at room temperature to release isocyanate and [PhBP3]Fe(CO)2. The [PhBP3]Fe(CO)2 byproduct is also a precursor to [PhBP3]FeNAr upon addition of aryl azide.