Four- and three-coordinate planar iron(ii) complexes supported by bulky organosilyl ligands

Abstract

The ligand exchange reaction of (THF)₂Fe[Si(SiMe₃)₃]₂ with 2 equivalents of an N-heterocyclic carbene (NHC) led to the formation of a square-planar iron(II) complex with trans-oriented –Si(SiMe₃)₃ ligands. Conversely, the introduction of a cis-coordinate bidentate organosilyl ligand instead of –Si(SiMe₃)₃ resulted in the formation of a square planar iron(II) complex supported by a cis-coordinate bidentate organosilyl ligand. A three-coordinate planar iron(II) bis(silyl) complex was also synthesized using a cis-coordinate bidentate organosilyl ligand and a cyclic (alkyl)(amino)carbene auxiliary ligand. Investigation of the catalytic performance of these complexes in the hydrosilylation of acetophenone revealed that the square-planar iron(II) complex with trans-oriented –Si(SiMe₃)₃ ligands exhibits superior reactivity relative to its tetrahedral precursor.