Reduction of Ketones with Silanes Catalysed by a Cyclopentadienyl-Functionalised N-Heterocyclic Iron Complex

The well-defined piano-stool iron(II) complex (Cp-NHC)Fe(CO)I bearing a bidentate cyclopentadienyl-functionalised N-heterocyclic carbene ligand is shown to catalyse the reduction of ketones under mild conditions (1-2 h at room temperature) when combined with catalytic amounts of potassium tert-butoxide, and using Ph2SiH2 and the inexpensive and less reactive polymethylhydrosiloxane as reducing agents. The stoichiometric reaction of (Cp-NHC)Fe(CO)I with potassium tert-butoxide generates an iron-hydroxo complex, which seems to be the active species in the reduction of ketones.