title: TMEDA in iron-catalyzed Kumada coupling: amine adduct versus homoleptic "ate" complex formation.
abstract: The reactions of iron chlorides with mesityl Grignard reagents and tetramethylethylenediamine (TMEDA) under catalytically relevant conditions tend to yield the homoleptic "ate" complex [Fe(mes)3 ](-) (mes=mesityl) rather than adducts of the diamine, and it is this ate complex that accounts for the catalytic activity. Both [Fe(mes)3 ](-) and the related complex [Fe(Bn)3 ](-) (Bn=benzyl) react faster with representative electrophiles than the equivalent neutral [FeR2 (TMEDA)] complexes. Fe(I) species are observed under catalytically relevant conditions with both benzyl and smaller aryl Grignard reagents. The X-ray structures of [Fe(Bn)3 ](-) and [Fe(Bn)4 ](-) were determined; [Fe(Bn)4 ](-) is the first homoleptic σ-hydrocarbyl Fe(III) complex that has been structurally characterized.
authors: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS (UK). r.bedford@bristol.ac.uk.
authors: Robin B
authors: RB
authors: Bedford
authors: Peter B
authors: PB
authors: Brenner
authors: Emma
authors: E
authors: Carter
authors: Paul M
authors: PM
authors: Cogswell
authors: Mairi F
authors: MF
authors: Haddow
authors: Jeremy N
authors: JN
authors: Harvey
authors: Damien M
authors: DM
authors: Murphy
authors: Joshua
authors: J
authors: Nunn
authors: Christopher H
authors: CH
authors: Woodall
keywords: Grignard reagents; catalysis; cross-coupling; iron