Sergeyev NM, Sergeyeva ND, Raynes WT
Department of Chemistry, Moscow State University, Moscow, 119899, Russia
J Magn Reson. 1999 Apr;137(2):311-315. doi: 10.1006/jmre.1998.1682.
The NMR spectra of solutions of 30% 17O-enriched H2O and D2O in nitromethane display the resonances of the three isotopomers H2O, HDO, and D2O. All 17O, 1H and 17O, 2H coupling constants and the primary and secondary isotope effects on J(17O, 1H) have been determined. The primary effect is -1.0 +/- 0.2 Hz and the secondary effect is -0.07 +/- 0.04 Hz. Using integrated intensities in the 17O NMR spectra, the equilibrium constant for the reaction H2O + D2O right harpoon over left harpoon 2HDO is found to be 3.68 +/- 0.2 at 343 K. From the relative integrated intensities of proton-coupled and -decoupled spectra the 17O-{1H} NOE is estimated for the first time, resulting in values of 0.908 and 0.945 for H2O and HDO, respectively. This means that dipole-dipole interactions contribute about 2.5% to the overall 17O relaxation rate in H2O dissolved in nitromethane. Copyright 1999 Academic Press.
30%富含17O的H2O和D2O在硝基甲烷中的溶液的核磁共振谱显示了三种同位素异构体H2O、HDO和D2O的共振峰。已测定了所有的17O、1H和17O、2H耦合常数以及对J(17O, 1H)的一级和二级同位素效应。一级效应为-1.0±0.2Hz，二级效应为-0.07±0.04Hz。利用17O核磁共振谱中的积分强度，发现在343K时反应H2O + D2O⇌2HDO的平衡常数为3.68±0.2。根据质子耦合和去耦合谱的相对积分强度，首次估算了17O-{1H}核Overhauser效应（NOE），结果H2O和HDO的该效应值分别为0.908和0.945。这意味着在溶解于硝基甲烷的H2O中，偶极-偶极相互作用对整体17O弛豫速率的贡献约为2.5%。版权所有1999年，学术出版社。
