Solution-phase synchrotron X-ray absorption spectroscopy (XAS) is a powerful tool for structural and mechanistic investigations of paramagnetic organoiron intermediates in solution-phase reactions. For paramagnetic organotransition metal intermediates, difficulties are often encountered with conventional NMR- and EPR-based analyses. By using solution-phase XAS, we succeeded in identifying the organoiron species formed in the reaction of iron bisphosphine with mesitylmagnesium bromide, MesMgBr, and 1-bromodecane in a [FeX2(SciOPP)]-catalyzed Kumada–Tamao–Corriu (KTC)-type cross-coupling reaction. X-ray absorption near-edge structure (XANES) spectra showed that the resulting aryliron species possessed a divalent oxidation state. Extended X-ray absorption fine structure (EXAFS) demonstrated that the solution-phase molecular geometries of these species are in satisfactory agreement with the crystallographic geometries of [FeIIBrMes(SciOPP)] and [FeIIMes2(SciOPP)]. By combining GC-quantitative analysis and solution-phase XAS, the cross-coupling reactivities of these aryliron species were successfully investigated in the reaction with 1-bromodecane under stoichiometric and catalytic conditions.
溶液相同步加速器 X 射线吸收光谱 (XAS) 是溶液相反应中顺磁性
有机铁中间体结构和机理研究的有力工具。对于顺磁性有机过渡
金属中间体,基于常规 NMR 和 EPR 的分析经常遇到困难。通过使用溶液相 XAS,我们成功地鉴定了
双膦铁与
溴化镁、MesMgBr 和 1-
溴癸烷在 [FeX2(Sci
OPP)] 催化的 Kumada-Tamao-Corriu (KTC) 反应中形成的
有机铁物质。型交叉偶联反应。 X射线吸收近边结构(XANES)光谱表明所得芳基
铁物种具有二价氧化态。扩展X射线吸收精细结构(EXAFS)表明这些物质的溶液相分子几何形状与[FeIIBrMes(Sci
OPP)]和[FeIIMes2(Sci
OPP)]的晶体几何形状非常一致。通过结合GC定量分析和溶液相XAS,在
化学计量和催化条件下成功地研究了这些芳基
铁物种在与1-
溴癸烷的反应中的交叉偶联反应性。