Structural and electrochemical analysis of FeCp* complexes supported by a borate-bridged dicarbene ligand

Abstract

We report three new FeCp* complexes (Cp* = pentamethylcyclopentadienyl) containing a bulky and electron rich borate-bridged ligand [Ph2B(tBuNHC)2]- (NHC = N-heterocyclic carbene). These (Ph2B(tBuNHC)2)FeCp* complexes are in three different spin states and are characterized using a combination of single crystal X-ray diffraction, cyclic voltammetry, NMR/IR spectroscopy, and topographic steric mapping. The combination of bulky tBu groups and Cp* enable the isolation of coordinatively unsaturated intermediate-spin FeII (S = 1) and FeIII (S = 3/2) complexes, while CO coordination to FeII furnishes a low spin (S = 0) adduct.