13C, 1H and 31P dynamic NMR studies of tetraalkyldiphosphanes: Barrier to internal rotation about the PP Bond in tetraisopropyldiphosphane
✍ Scribed by J. P. Albrand; A. Cogne; C. Taieb
- Publisher
- John Wiley and Sons
- Year
- 1983
- Tongue
- English
- Weight
- 572 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
The ^1^H, ^31^P and ^13^C NMR spectra of tetramethyldiphosphane (1), tetraethyldiphosphane (2) and tetraisopropyldiphosphane (3) have been studied in the temperature range 30 to −150°C and at magnetic induction up to 5.87 T. In the range −100 to −135 °C, the ^1^H and ^13^C spectra of 3 show important changes which can be attributed to freezing the interconversion between two equivalent non‐trans conformations. The line shape analysis of the ^13^C signals leads to Δ__G__^≠^ = 29.4 kJ mol^−1^ at −113 °C for the dynamic process involved. The spin coupling parameters ^1^J(PP) and N(PC) = ^1^J(PC) + ^2^J(PC) observed for 1 in the temperature range 30 to −120 °C show variations which could be due to a preference for the trans conformation in this diphosphane.