| Autor: |
Zhang, Jing, Siu, Kam, Lin, Chin H., Canary, James W. |
| Zdroj: |
New Journal of Chemistry; 2005, Vol. 29 Issue: 9 p1147-1151, 5p |
| Abstrakt: |
The dynamics of molecular conformational changes for Cui complexes of two tripodal ligands were studied. Variable-temperature NMR and circular dichroism in combination with two-dimensional NMR experiments were employed to determine the structural and energetic details of a dynamic process in which one of three arms dissociates from coordination to Cui. Dissociation was triggered by addition of a strongly coordinating anion SCN−. One-electron oxidation to the Cuii complex returned coordination of all three ligand arms. The observed phenomena were dependent upon steric crowding; addition of a single methyl group to one arm resulted in marked differences in behavior. The CuSCN and CuPF6complexes of tris2-quinolylmethylamine TQA and the CuPF6complex of 1-quinolin-2-yl-N,N-bisquinolin-2-ylmethylethanamine MeTQA did not give any evidence for differences in coordination over the temperature range 0–35 °C, while CuIMeTQANCS demonstrated marked differences in NMR but not CD spectra over this temperature range. In the latter complex, two diastereotopic arms displace each other with a transition energy of 14.0 kcal mol−1. The structure of the arm-dissociated complex contains a higher degree of stereochemical complexity than the tetradentate complexes. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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