Nonadditivity of D/H isotope effects on 13C chemical shifts in halomethanes

Nonadditivity in the values of the 13C isotope shifts for successive D/H replacements has been measured. The compounds studied are dichloromethane, dibromomethane, bromomethane and iodomethane. In all cases deviations from additivity, defined as the differences between the experimental isotope shifts and those obtained from the additive approach, were found to be negative (on the δ-scale) and to be of order 1-4 ppb. The nonadditivity may be explained using the approach proposed by Jameson and Osten and based on the idea of different secondary geometrical isotope effects produced by deuterium on the neighbouring CH and CD bond lengths. However, this approach requires unrealistically large difference in these secondary geometrical effects. An alternative approach based on recently calculated CH and CD bond displacements is proposed where nonadditivities may be attributed to small quadratic corrections to the secondary geometrical effects. © 1994.

Авторы
Sergeyev N.M.1 , Sergeyeva N.D. 2 , Raynes W.T.3
Редакторы
-
Издательство
Elsevier
Номер выпуска
5-6
Язык
Английский
Страницы
385-392
Статус
Опубликовано
Подразделение
-
Номер
-
Том
221
Год
1994
Организации
  • 1 NMR Laboratory, Department of Chemistry, Moscow State University, 119899 Moscow, Russian Federation
  • 2 Organic Chemistry Division, University of People's Friendship, Miklukho-Maklai, 6, 117302 Moscow, Russian Federation
  • 3 Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, United Kingdom
Ключевые слова
-
Дата создания
19.10.2018
Дата изменения
19.10.2018
Постоянная ссылка
https://repository.rudn.ru/ru/records/article/record/946/