Synthesis and characterization of a sterically encumbered homoleptic tetraalkyliron(III) ferrate complex

Homoleptic iron-alkyl complexes have been implicated as key intermediates in iron-catalyzed cross coupling with simple iron salts. Tetraalkyliron(II1) ferrate species have been shown to be accessible with either methyl or benzyl ligands, where the former complex is S = 3/2 and distorted square planar while the latter is a S= 5/2 distorted tetrahedral species. In the current study, a new tetraalkyliron(III) complex is synthesized containing modified methylene substituents that incorporate large trimethylsilyl (TMS) groups to further probe steric and electronic ligand effects in tetraalkyliron(III) complexes by increasing the electron-donating ability of the ligand while retaining steric bulk. Detailed structural and DFT studies provide insight into electronic structure and bonding of the four-coordinate trimethylsilylmethyl iron(III) complex compared to the previously reported analogs containing methyl and benzyl ligands. (C) 2018 Elsevier Ltd. All rights reserved.