| 118169-94-1

• 分子结构分类: 有机化合物 - 有机盐
• CAS: 118169-94-1
• 化学式: C₆H₂₄CrN₆
• 分子量: 244.197
• InChiKey: AYDADBTUMBSASW-CKQGYFMESA-N

计算性质

• 辛醇/水分配系数(LogP)：
  None
• 重原子数：
  None
• 可旋转键数：
  None
• 环数：
  None
• sp3杂化的碳原子比例：
  None
• 拓扑面积：
  None
• 氢给体数：
  None
• 氢受体数：
  None

反应信息

• 作为产物：
  描述：

  铬三乙二胺 、 重水 以 重水 为溶剂， 生成
  参考文献：
  名称：

  Metal ion-biomolecule interactions. Part 22.¹ Cr(III)-catalyzed isotopic hydrogen e×change in methylimidazoles

  摘要：

  The detritiation kinetics of the Cr(III) complexes 1 and 3-6 have been studied in aqueous buffers at 35 degrees C, using the liquid scintillation counting technique. Results for 5 and 6 provide benchmark kinetic data for N-T/N-H exchange under the experimental conditions of the study and have aided in the delineation of N-T/N-H from C-T/C-H exchange in the parallel reactions observed experimentally. Curved first-order plots obtained for 1, 3, and 4 were treated to yield rate constants for two parallel exchange reactions k(obs)(A) and k(obs)(B) for the "fast" and "slow" processes, respectively. The "fast" process has been assigned to C(2)-H exchange in 1, competing N-H and C(2)-H exchange in 3, and N-H exchange in 4. In all cases, the "slow" process is associated with C(4,5)-H exchange. Identification of exchange sites in 1, 3, and 4 was made possible by the consideration of the results of an IR spectroscopic study of hydrogen-deuterium exchange, comparison of the extent of H-3 incorporatation in different complexes in the tritiation experiments, and a careful analysis of the exchange kinetic data. Analysis of the rate data indicates that Cr(III) significantly enhances C(2)-H exchange in 1 and 3, while C(4,5)-H exchange, hitherto reported in the literature only under drastic reaction conditions, was observed for 1, 3, and 4 under the mild conditions of the present study. Quantitation of the effect of Cr(III) coordination on H-3 exchange in imidazole-type nuclei was achieved fully in 1; giving k(M+) values of 6 + 10(3) and 7 x 10(2) M(-1)s(-1) for C(2)-H and C(4,5)-H exchange, respectively. Using the literature value for k(H+), the second-order rate constant for C(2)-H exchange under H+ catalysis, 2.9 x 10(2) M(-1)s(-1), it follows that Cr(III) is ca. 20 times better as a catalyst for C(2)-H exchange in 1-methylimidazole than H+, providing the first example of a metal ion being more effective than a proton in these processes. Comparison of the results obtained with 1 with literature results for 2 shows a very large (ca. 3 x 10(5)-fold) difference in the catalytic activities of Cr(III) and Co(III), favouring the former. The dichotomy in the effectiveness of the two metal ions in catalyzing H-3 exchange in the imidazole nucleus has been ascribed to differences in (i) extent of Mn+-N bond polarization (and the consequent effect on ligand C-H acidity); (ii) electronic configuration; (iii) crystal field stabilization and activation energies; and (iv) importance of metal-ligand pi back-bonding. The study highlights the diversity of factors and complexity of interactions involved in determining the role of metal ions in biological systems, especially where such processes involve complex formation between metal ions and heterocyclic fragments of biomolecules.

  DOI：

  10.1139/cjc-78-4-474

文献信息

• Neporent, I. B.; Sveshnikova, E. B., Russian Journal of Inorganic Chemistry, 1979, vol. 24, p. 391 - 394
  作者：Neporent, I. B.、Sveshnikova, E. B.

  DOI：——

  日期：——