852142-68-8Relevant academic research and scientific papers
TMEDA in iron-catalyzed Kumada coupling: Amine adduct versus homoleptic "ate" complex formation
Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Cogswell, Paul M.,Haddow, Mairi F.,Harvey, Jeremy N.,Murphy, Damien M.,Nunn, Joshua,Woodall, Christopher H.
supporting information, p. 1804 - 1808 (2014/03/21)
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. FeI 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 FeIII complex that has been structurally characterized. Casting iron in catalytic roles: Chelating diamine ligands such as TMEDA are routinely used in iron-catalyzed cross-coupling reactions of aryl Grignard reagents. However, it was found that under catalytically relevant conditions, there is little evidence for their coordination to iron centers; homoleptic anionic organoiron species are produced instead. Copyright
Square planar vs tetrahedral geometry in four coordinate iron(II) complexes
Hawrelak, Eric J.,Bernskoetter, Wesley H.,Lobkovsky, Emil,Yee, Gordon T.,Bill, Eckhard,Chirik, Paul J.
, p. 3103 - 3111 (2008/10/09)
The geometric preferences of a family of four coordinate, iron(II) d 6 complexes of the general form L2FeX2 have been systematically evaluated. Treatment of Fe2(Mes)4 (Mes = 2,4,6-Me3C6H2) with monodentate phosphine and phosphite ligands furnished square planar trans-P2Fe(Mes) 2 derivatives. Identification of the geometry has been accomplished by a combination of solution and solid-state magnetometry and, in two cases (P = PMe3, PEt2Ph), X-ray diffraction. In contrast, both tetrahedral and square planar coordination has been observed upon complexation of chelating phosphine ligands. A combination of crystallographic and magnetic susceptibility data for (depe)Fe-(Mes)2 (depe = 1,2- bis(diethylphosphino)ethane) established a tetrahedral molecular geometry whereas SQUID magnetometry and Moessbauer spectroscopy on samples of (dppe)Fe(Mes)2 (dppe = 1,2-bis(diphenylphosphino)-ethane) indicated a planar molecule. When dissolved in chlorinated solvents, the latter compound promotes chlorine atom abstraction, forming tetrahedral (dppe)Fe(Mes)Cl and (dppe)FeCl2. Ligand substitution reactions have been studied for both structural types and are rapid on the NMR time scale at ambient temperature.
