Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein, 9300, Republic of South Africa.
Dalton Trans. 2011 Jun 14;40(22):5844-51. doi: 10.1039/c1dt00013f. Epub 2011 Mar 21.
A series of ferrocene-containing rhodium complexes of the type [Rh(FcCOCHCOR)(cod)] (cod = 1,5-cyclooctadiene) with R = CF(3), 1, (E(pa)(Rh) = 269; E(o)'(Fc) = 329 mV vs. Fc/Fc(+)), CCl(3), 2, (E(pa) = 256; E(o)' = 312 mV), CH(3), 3, (E(pa) = 177; E(o)' = 232 mV), Ph = C(6)H(5), 4, (E(pa) = 184; E(o)' = 237 mV), and Fc = ferrocenyl = (C(5)H(5))Fe(C(5)H(4)), 5, (E(pa) = 135; E(o)'(Fc1) = 203; E(o)'(Fc2) = 312 mV), have been studied electrochemically in CH(3)CN. Results indicated that the rhodium(I) centre is irreversibly oxidised to Rh(III) in a two-electron transfer process before the ferrocenyl fragment is reversibly oxidized in a one-electron transfer process. The peak anodic (oxidation) potential, E(pa), (in V vs. Fc/Fc(+)) of the rhodium core in 1-5 relates to k(2), the second-order rate constant for the substitution of (FcCOCHCOR)(-) with 1,10-phenanthroline in [Rh(FcCOCHCOR)(cod)] to form Rh(phen)(cod) in methanol at 25 °C with the equation lnk(2) = 39.5 E(pa)(Rh) - 3.69, while the formal oxidation potential of the ferrocenyl groups in 1-5 relates to k(2) by lnk(2) = 40.8 E(o)'(Fc)-6.34. Complex 4 (IC(50) = 28.2 μmol dm(-3)) was twice as cytotoxic as the free FcCOCH(2)COPh ligand having IC(50) = 54.2 μmol dm(-3), but approximately one order of magnitude less toxic to human HeLa neoplastic cells than cisplatin (IC(50) = 2.3 μmol dm(-3)).
一系列含有二茂铁的铑配合物，类型为[Rh（FcCOCHCOR）（cod）]（cod=1,5-环辛二烯），其中 R = CF3，1，（E（pa）（Rh）=269；E（o）'（Fc）=329 mV 与 Fc/Fc（+）相比），CCl3，2，（E（pa）=256；E（o）'=312 mV），CH3，3，（E（pa）=177；E（o）'=232 mV），Ph = C6H5，4，（E（pa）=184；E（o）'=237 mV）和 Fc = 二茂铁基=（C5H5）Fe（C5H4），5，（E（pa）=135；E（o）'（Fc1）=203；E（o）'（Fc2）=312 mV），在 CH3CN 中进行了电化学研究。结果表明，在铁（II）中心不可逆氧化为 Rh（III）的过程中，二茂铁片段在一电子转移过程中可逆氧化。在 1-5 中，铑核的峰阳极（氧化）电位 E（pa）（相对于 Fc/Fc（+））与 k2 有关，k2 是[Rh（FcCOCHCOR）（cod）]中（FcCOCHCOR）-与 1,10-菲咯啉取代的二级速率常数，在 25°C 下在甲醇中形成[Rh（phen）（cod）]+，方程为 lnk2=39.5 E（pa）（Rh）-3.69，而 1-5 中二茂铁基的形式氧化电位通过 lnk2=40.8 E（o）'（Fc）-6.34 与 k2 相关。与游离的 FcCOCH（2）COPh 配体（IC50=54.2 μmol dm-3）相比，化合物 4（IC50=28.2 μmol dm-3）的细胞毒性增加了一倍，但对人 HeLa 肿瘤细胞的毒性比顺铂（IC50=2.3 μmol dm-3）低一个数量级。
