The synthesis and characterization of three compounds [Rh(η⁵-C₅Me₅)Cl(N^N)]PF₆ (N^N=4,4’-disubstituted-2,2’-bipyridines, 1–3) are described. The cationic complexes contain the bidentate ligands N^N=4,4'-di-tert-butyl-2,2'-bipyridine (1), N^N=4,4'-dinonyl-2,2'-bipyridine (2) and N^N=4,4'-diamino-2,2'-bipyridine (3). The complex salts were obtained by the bridge-splitting reaction from the precursor [{Rh(η⁵-C₅Me₅)(μ-Cl)Cl}₂] and subsequent salt metathesis affording their corresponding hexafluorido phosphate salts. All compounds were characterized by elemental analysis and spectroscopic means. Additionally, the molecular structure of compound 3 in the solid was determined by a single-crystal X-ray diffraction study. The cytotoxicity of all three compounds was examined by MTT assay against two cancer cell lines – HT-29 (colon adenocarcinoma) and MCF-7 (human breast adenocarcinoma) - and normal human fibroblast cells (GM5657T). Compound 1 has moderate cytotoxicity against both cell lines, while compound 2 is seven to nine times more cytotoxic than cisplatin against MCF-7 and HT-29, respectively. In contrast to cisplatin, both compounds are more active against cancer cells than fibroblasts, thus showing some cancer selectivity.

中文翻译：

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一些含有4,4'-二取代-2,2'-联吡啶配体的半夹心铑(III)配合物的细胞毒活性

^{三种化合物[Rh(η 5} -C ₅ Me ₅ )Cl(N^N)]PF ₆ (N^N=4,4'-二取代-2,2'-联吡啶, 1–3 )的合成与表征被描述。阳离子配合物含有二齿配体 N^N=4,4'-二叔丁基-2,2'-联吡啶 ( 1 )、N^N=4,4'-二壬基-2,2'-联吡啶 ( 2 ) 和 N^N=4,4'-二氨基-2,2'-联吡啶 ( 3 )。通过前体[{Rh(η ⁵ -C ₅ Me ₅ )(μ-Cl)Cl} ₂ ]的桥断裂反应和随后的盐复分解反应获得其相应的六氟磷酸盐，从而获得复合盐。所有化合物均通过元素分析和光谱手段进行表征。此外，通过单晶 X 射线衍射研究确定了固体中化合物3的分子结构。通过 MTT 测定检测所有三种化合物对两种癌细胞系——HT-29（结肠腺癌）和 MCF-7（人乳腺癌）以及正常人成纤维细胞（GM5657T）的细胞毒性。化合物1对两种细胞系均具有中等细胞毒性，而化合物2对 MCF-7 和 HT-29 的细胞毒性分别是顺铂的 7 至 9 倍。与顺铂相比，这两种化合物对癌细胞的活性比对成纤维细胞的活性更强，因此表现出一定的癌症选择性。