ENHANCEMENT OF ASYMMETRY EFFECTS IN NMR BY INTERMOLECULAR HYDROGEN BONDING

被引：3
作者：
GARRISON, AW
KEITH, LH
ALFORD, AL
机构：
[1] U.S. Department of the Interior, Federal Water Pollution Control Administration Southeast, Water Laboratory, Athens
来源：
SPECTROCHIMICA ACTA PART A-MOLECULAR SPECTROSCOPY | 1969年 / A 25卷 / 01期
关键词：
D O I：
10.1016/0584-8539(69)80172-8
中图分类号：
O433 [光谱学];
学科分类号：
0703 ; 070302 ;
摘要：
The doubling of the NMR signals of the isopropyl methyl protons in 2,4-dichlorophenyl methyl isopropylphosphoramidate has been shown to be due to a difference in chemical shift of the two methyl groups. This difference is ascribed to a steric hindrance to rotation about the N-C bond which enhances the inherent nonequivalence due to molecular asymmetry. Studies of the changes in chemical shift difference with changes in temperature, concentration and solvent show the steric hindrance to be due to intermolecular hydrogen bonding. The NMR data are correlated with infrared spectra of the phosphoramidate obtained under similar conditions; these spectra support the hydrogen bonding hypothesis. Possible hydrogenbonded species are discussed. © 1969.
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页码：77 / &
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