HOCCO versus OCCO: Comparative spectroscopy of the radical and diradical reactive intermediates.
HOCCO versus OCCO: Comparative spectroscopy of the radical and diradical reactive intermediates.
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HOCCO 与 OCCO：自由基和双自由基反应中间体的比较光谱。
DOI：
10.1063/1.4953774
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
A. Sanov
中科院分区：
文献类型：
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作者：
Andrew R. Dixon;Tian Xue;A. Sanov
我们对三种乙二醛衍生物进行了光电子成像研究：乙二酮阴离子（OCCO（-））、乙二内酯（HOCCO（-））和乙二醛（OHCCO（-））。这些阴离子提供了相应的中性活性中间体的通道：OCCO双自由基和HOCCO和OHCCO自由基。与O（-）与乙二醛（OHCHO）反应中的直接去质子化途径（预期产生glycopride（OHCCO（-）相比，OHCCO（-）显示为次要产物，HOCCO（-）是m/z = 57阴离子的主要观察到的异构体。在HOCCO/OHCCO阴离子光电子能谱中，我们确定了该自由基体系的几个电子态，并确定了HOCCO的绝热电子亲合能为1.763（6）eV。将该结果与我们最近对这种瞬态双自由基的研究中报道的乙二胺（OCCO）的相应1.936（8）eV值进行了比较[A. R.狄克逊，T. Xue和A. Sanov，Angew.化学成分：Int.Ed.54，8764-8767（2015）]。通过对HOCCO（-）/OHCCO（-）和OCCO（-）光电子能谱的比较，讨论了OCCO中连接在碳骨架上的氢或末端氧的对比效应。
We present a photoelectron imaging study of three glyoxal derivatives: the ethylenedione anion (OCCO(-)), ethynediolide (HOCCO(-)), and glyoxalide (OHCCO(-)). These anions provide access to the corresponding neutral reactive intermediates: the OCCO diradical and the HOCCO and OHCCO radicals. Contrasting the straightforward deprotonation pathway in the reaction of O(-) with glyoxal (OHCCHO), which is expected to yield glyoxalide (OHCCO(-)), OHCCO(-) is shown to be a minor product, with HOCCO(-) being the dominant observed isomer of the m/z = 57 anion. In the HOCCO/OHCCO anion photoelectron spectrum, we identify several electronic states of this radical system and determine the adiabatic electron affinity of HOCCO as 1.763(6) eV. This result is compared to the corresponding 1.936(8) eV value for ethylenedione (OCCO), reported in our recent study of this transient diradical [A. R. Dixon, T. Xue, and A. Sanov, Angew. Chem., Int. Ed. 54, 8764-8767 (2015)]. Based on the comparison of the HOCCO(-)/OHCCO(-) and OCCO(-) photoelectron spectra, we discuss the contrasting effects of the hydrogen connected to the carbon framework or the terminal oxygen in OCCO.