Four-coordinate, 14-electron iron alkyl complexes supported by the tripodal phosphine ligand [PhB(CH_2PiPr_2)_3]^-

Abstract

Recent work in our laboratories has focused on the use of tridentate, anionic phosphine ligands to promote novel reactivity of the late transition metals. The highly electron-releasing, sterically demanding tris(diisopropylphosphino)borate ligand, [PhBP^(iPr3)] ([PhBP^(iPr3)]=[PhB(CH_2PiPr_2)_3]^- has been shown to stabilize coordinatively unsaturated iron complexes with a variety of oxidation states. While 18-electron iron alkyl species are known, four-coordinate, low-electron-count iron alkyl complexes are relatively rare. It was of interest to synthesize monoalkyl complexes on the [PhBP^(ipr3)]Fe platform because of their potential use as carbene precursors. A series of four-coordinate, 14-electron iron(ll) alkyl complexes have been synthesized. The complexes have been characterized by a variety of spectroscopic and electrochemical methods as well as x-ray crystallography. The characterization and reactivity of the alkyl complexes will be described.