Tuning of Redox Properties for the Design of Ruthenium Anticancer Drugs: Part 2. Syntheses, Crystal Structures, and Electrochemistry of Potentially Antitumor [RuIII/IICl6-
详细信息 查看全文
- 作者：Erwin Reisner ; Vladimir B. Arion ; Anna Eichinger ; Norbert Kandler ; Gerald Giester ; Armando J. L. Pombeiro ; and Bernhard K. Keppler
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：September 19, 2005
- 年：2005
- 卷：44
- 期：19
- 页码：6704 - 6716
- 全文大小：323K
- 年卷期：v.44,no.19(September 19, 2005)
- ISSN：1520-510X
文摘
A series of mixed chloro-azole ruthenium complexes with potential antitumor activity, viz., mer-[RuIIICl3(azole)3] (B),trans-[RuIIICl2(azole)4]Cl (C), trans-[RuIICl2(azole)4] (D), and [RuII(azole)6](SO3CF3)2 (E), where azole = 1-butylimidazole(1), imidazole (2), benzimidazole (3), 1-methyl-1,2,4-triazole (4), 4-methylpyrazole (5), 1,2,4-triazole (6), pyrazole(7), and indazole (8), have been prepared as a further development of anticancer drugs with the general formula[RuCl4(azole)2]- (A). These compounds were characterized by elemental analysis, IR spectroscopy, electronicspectra, electrospray mass spectrometry, and X-ray crystallography. The electrochemical behavior has been studiedin detail in DMF, DMSO, and aqueous media using cyclic voltammetry, square wave voltammetry, and controlledpotential electrolysis. Compounds B and a number of C complexes exhibit one RuIII/RuII reduction, followed, at asufficiently long time scale, by metal dechlorination on solvolysis. The redox potential values in organic mediaagree with those predicted by Lever's parametrization method, and the yet unknown EL parameters were estimatedfor 1 (EL = 0.06 V), 3 (EL = 0.10 V), 4 (EL = 0.17 V), and 5 (EL = 0.18 V). The EL values for the azole ligands1-8 correlate linearly with their basicity (pKa value of the corresponding azolium acid H2L+). In addition, a logarithmicdependence between the homogeneous rate constants for the reductively induced stepwise replacement of chloroligands by solvent molecules and the RuIII/RuII redox potentials was observed. Lower E1/2 values (higher net electrondonor character of the ligands) result in enhanced kinetic rate constants of solvolysis upon reduction. The effectof the net charge on the RuIII/RuII redox potentials in water is tentatively explained by the application of the Bornequation. In addition, the pH-dependent electrochemical behavior of trans-[RuCl2(1,2,4-triazole)4]Cl is discussed.