Selective Conversion of CO₂ into Isocyanate by Low‐Coordinate Iron Complexes

Abstract

Discovery of the mechanisms for selective transformations of CO2 into organic compounds is a challenge. Herein, we describe the reaction of low‐coordinate Fe silylamide complexes with CO2 to give trimethylsilyl isocyanate and the corresponding Fe siloxide complex. Kinetic studies show that this is a two‐stage reaction, and the presence of a single equivalent of THF influences the rates of both steps. Isolation of a thermally unstable intermediate provides mechanistic insight that explains both the effect of THF in this reaction, and the way in which the reaction achieves high selectivity for isocyanate formation.

A Molecular Low‐Coordinate [Fe‐S‐Fe] Unit in Three Oxidation States

“…Exposure of 2 to CO 2 causedavisible colour change but did not yield any identifiable product, probably due to parallel insertion of CO 2 into the iron silylamide bonds. [22] As such we examined the behavior of 2 towardst he heavierc ongener CS 2 ,w hich is an inhibitor of nitrogenasemediated protono ra cetylene reduction but can also serve as as ubstrate that is mainly converted to H 2 S. [23][24][25] This led to the isolation of the monomeric iron thiocarbonate complex (K{18c6}) 2 [Fe(h 2 -CS 3 )L 2 ], 5 (Scheme 3, Figure 6).…”