Gas-Phase Formation and Fragmentation Reactions of the Organomagnesates [RMgX2]−
Gas-Phase Formation and Fragmentation Reactions of the Organomagnesates [RMgX2]−
复制标题
有机镁盐 [RMgX2]− 的气相形成和裂解反应
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
R. O'hair
中科院分区：
文献类型：
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作者：
George N. Khairallah;C. C. Thum;D. Lesage;J. Tabet;R. O'hair
通过羧酸镁前体 [RCO2MgX2]− 的脱羧作用，在气相中生成一系列单核有机镁盐 [RMgX2]−（R = Me、Et、Pr、iPr、tBu、乙烯基、烯丙基、HC≡C、Ph、PhCH2、PhCH2CH2；X = Cl、Br、I）。通过在线性离子阱和三重四极杆质谱仪中进行的实验以及 DFT 计算相结合，检查了这些有机镁酸盐的气相形成和单分子反应性。发现卤化物损失与单核 [RMgX2]− 形成中的脱羧直接竞争。然而，可以采用空间不受阻碍、稳定的 R- 取代基和强 Mg-Cl 键来促进脱羧反应，但会牺牲卤化物损失通道。因此，在 R = HCeqC, PhCH2 的情况下，脱羧是主要的裂解途径。对所得单核有机镁盐[RMgX2]−进行质量选择，并检查其单分子化学。观察到四种竞争性断裂：键均裂、键异裂……
A range of mononuclear organomagnesates [RMgX2]− were generated in the gas phase by decarboxylation of the magnesium carboxylate precursors [RCO2MgX2]− (R = Me, Et, Pr, iPr, tBu, vinyl, allyl, HC≡C, Ph, PhCH2, PhCH2CH2; X = Cl, Br, I). The gas-phase formation and unimolecular reactivity of these organomagnesates were examined using a combination of experiments carried out in linear ion trap and triple-quadrupole mass spectrometers and DFT calculations. Halide loss was found to directly compete with decarboxylation in the formation of mononuclear [RMgX2]−. However, sterically unhindered, stable R– substituents and strong Mg–Cl bonds can be employed to facilitate the decarboxylation reaction at the expense of the halide loss channel. Thus, in the case of R = HC≡C, PhCH2, decarboxylation is the main fragmentation pathway. The resultant mononuclear organomagnesates [RMgX2]− were mass-selected, and their unimolecular chemistry was examined. Four competing fragmentations were observed: bond homolysis, bond hete...