1-降冰片基阳离子可能与2-降冰片基阳离子处于平衡状态

IF 2.1 4区化学 Q3 CHEMISTRY, PHYSICAL

Progress in Reaction Kinetics and Mechanism Pub Date : 2019-08-22 DOI:10.1177/1468678319861319

A. Mamantov

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引用次数: 0

摘要

在稳定离子条件下，例如SbF5/SO2F2/SO2ClF，−80 oC下，2-Nb阳离子的1H和13C NMR 400 MHZ谱显示，除了通常的1H NMR共振δ 4.93, 2.82, 1.85外，还显示了从未见过的单重态δ 9.63和双重态δ 2.97 (j2,6 = 16.6 Hz)，比值为1.00:1.07，提出这是由于共振稳定桥头堡1-Nb阳离子对映体与2-Nb阳离子平衡所致。对应的13C质子耦合核磁共振谱，−80 oC，具有C3,5,7三重态，δ 30.45, J(CH) = 139.14 Hz，和C4双重态，δ 37.7, J(CH) = 154.54 Hz。C1,2,6吸收δ 91.04相对较宽，而以前在- 70℃时，它是一个五联体。−80℃下13C质子解耦谱显示C4双重态和C3,5,7三重态坍缩成单重态，但C1,2,6共振仍然很宽。分析支持在≤-159℃时，共振稳定的对映体2-阳离子之间的交换减慢。提出了今后的研究方向。

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1-Norbornyl cation may be in equilibrium with 2-norbornyl cation

New 1H and 13C NMR 400 MHZ spectra of the 2-Nb cation under stable ion conditions, for example, in SbF5/SO2F2/SO2ClF, −80 oC, show besides the usual 1H NMR resonances at δ 4.93, 2.82, 1.85, the never before seen singlet, δ 9.63, and doublet, δ 2.97 (J2,6 = 16.6 Hz), ratio 1.00 : 1.07, proposed to be due to resonance-stabilized bridgehead 1-Nb cationic enantiomers in equilibrium with 2-Nb cation. The corresponding 13C proton-coupled NMR spectrum, −80 oC, has a C3,5,7 triplet, δ 30.45, J(CH) = 139.14 Hz, and C4 doublet, δ 37.7, J(CH) = 154.54 Hz. The C1,2,6 absorption, δ 91.04 is relatively broad, whereas previously, at −70 oC, it was a pentuplet. The 13C proton-decoupled spectrum at −80 oC shows the C4 doublet and C3,5,7 triplet collapsed to a singlet, but the C1,2,6 resonance is still broad. Analyses support the slowing exchange between resonance stabilized enantiomeric 2-cations at ≤ –159 oC. Some future studies are proposed.

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来源期刊

Progress in Reaction Kinetics and Mechanism 化学-物理化学

CiteScore

2.10

自引率

0.00%

发文量

审稿时长

2.3 months

期刊介绍： The journal covers the fields of kinetics and mechanisms of chemical processes in the gas phase and solution of both simple and complex systems.