| Autor: |
Schulz, Volker, Frick, Axel, Huttner, Gottfried |
| Zdroj: |
European Journal of Inorganic Chemistry; December 2002, Vol. 2002 Issue: 12 p3111-3128, 18p |
| Abstrakt: |
Eleven solid state structures of eight compounds 1−8 of the type [{κ-PAr2CH2CH(OH)CH2-κ-PAr'2}Rh-(η4-COD)]+PF6− are used as a basis for deriving a force field model for this class of compound by Genetic Algorithms. By a complete search in the conformational space of [{κ-PMes2CH2CH(OH)CH2-κ-PPh2}Rh-(η4-COD)]+PF6− (1) it is shown that the model is not only capable of reproducing the structures but as well capable to predict the stability of individual conformers and the conformational reaction pathways in full agreement with experimental observations. The model predicts that the λ twist conformation is the most stable conformation of 1. The δ twist conformation is calculated 3.1 kJ·mol−1 above this minimum. The experimental value is 3.4 kJ·mol−1. The model predicts that there are two mechanistic pathways for the λ &rlarr2; δ isomerization process. Both of them are characterised by a strictly coupled rotation of the mesityl groups of the PMes2 entity of 1. These two pathways differ only in the sense of this rotation. The activation enthalpy for the λ &rlarr2; δ isomerization process as a whole is calculated as ΔH# = 69.1 kJ·mol−1. The experimental value is ΔH# = 64.4 kJ·mol−1. It is concluded therefore that the novel type of approach as described leads to models of very high predictive power. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002) |
| Databáze: |
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