A TRIR, TREPR and Computational Study on the Reactivity and Structure of the 2,2,2-Trifluoroethoxycarbonyl Radical†
作者:Christoph Kolano、Götz Bucher、Dirk Grote、Olaf Schade、Wolfram Sander
DOI:10.1562/2005-05-30-ra-554
日期:——
in conformations that are s-trans or s-cis with respect to the R-O-C(O) x dihedral. A comparison of experimental TREPR spectra with simulations indicates that the s-trans conformer is observed in the case of the ethoxycarbonyl radical, 3a. In the case of the trifluorethoxycarbonyl radical, 3b, however, the additional proton HFS observed shows that it is the s-cis conformer that is formed. As calculations
通过在四氯化碳和乙腈溶液中脉冲辐射9-芴酮肟2,2,2-三氟乙基草酸酯1b生成了2,2,2-三氟乙氧基羰基3b。它的特征在于时间分辨电子顺磁共振光谱(EPR)和红外光谱。自由基的寿命在微秒范围内,可以在我们的时间分辨设备的上升时间内检测到,然后再进行重组或与溶剂反应。没有观察到脱羰或脱羧。在氧的存在下,自由基被淬灭以产生2,2,2-三氟乙氧基羰基过氧自由基4b,其寿命再次在几微秒的范围内。时间分辨电子顺磁共振波谱(TREPR)允许以1:1:1的比例进行检测 在g = 2.0032时,芴9-亚甲基基团7的1个三联体和在1 = 3:3:1的四重态中,由于三氟乙氧基羰基基团3b在g = 2.001时的质子偶联,具有额外的超精细分裂(HFS)。计算表明,相对于ROC(O)x二面体,烷氧基羰基可以以反式或顺式构型存在。实验TREPR光谱与模拟结果的比较表明,在乙氧基羰基3a的情况下观察到了s-反式构