Dynamic properties of p-diiodobenzene investigated by solid-state2H and13C nuclear magnetic resonance spectroscopy
| Autor: | Xavier Alcobéa, Abil E. Aliev, Kenneth D. M. Harris, E. Estop |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Arrhenius equation
Phase transition symbols.namesake Carbon-13 NMR satellite Chemistry symbols Analytical chemistry Orthorhombic crystal system Nuclear magnetic resonance crystallography Nuclear magnetic resonance spectroscopy Physical and Theoretical Chemistry Atmospheric temperature range Two-dimensional nuclear magnetic resonance spectroscopy |
| Zdroj: | J. Chem. Soc., Faraday Trans.. 89:3797-3800 |
| ISSN: | 1364-5455 0956-5000 |
| Popis: | p-Diiodobenzene exists in two crystalline phases, both of which are orthorhombic, with space groups Pbca(α phase) and Pccn(β phase) respectively. The α phase is the stable form at ambient temperature, and a phase transition to the β phase occurs at ca. 326 K. In this paper, we present variable-temperature solid-state 2H NMR studies of perdeuteriated p-diiodobenzene. Over the temperature range 293–320 K, the 2H NMR spectrum of the α phase is a rigid lattice powder pattern, with static quadrupole coupling constant 176 ± 1 kHz and static asymmetry parameter 0.04 ± 0.01. Over the temperature range 350–370 K, the 2H NMR spectrum of the β phase shows features characteristic of 180° jumps of the aromatic ring about the C(1)–C(4) axis, and the jump frequency (κ) for this motion has been determined as a function of temperature. On the assumption of Arrhenius behaviour for the temperature dependence of κ, the activation energy for this jump motion is estimated to be (90 ± 10) kJ mol–1. The temperature-dependent structural properties of perdeuteriated p-diiodobenzene have also been investigated by high-resolution solid-state 13C NMR spectroscopy, and results from these investigations are reported and discussed in the light of the dynamic information determined from the 2H NMR studies. |
| Databáze: | OpenAIRE |
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