Three [(η⁶-arene)RuC₂B₉H₁₁] complexes (arene = p-cymene (2), biphenyl (3) and 1-Me-4-COOEt-C₆H₄ (4)) were synthesised according to modified literature procedures and fully characterised. 2–4 were found to be moderately active against two types of tumour cell lines (HCT116 and MCF7), with IC₅₀ values in the low micromolar range. However, viability of normal, healthy cells (MRC-5 cell line, MLEC and mouse macrophages) was not affected by treatment with 2–4, indicating high selectivity of the metallacarborane complexes towards tumour cell lines, compared to the unselective antitumour agent cisplatin and other potential Ru^II drugs. Moreover, flow cytometric analysis suggested that 4 induces cell death via a caspase-dependent apoptotic mechanism. DFT calculations of the frontier molecular orbitals showed that the HOMO–LUMO gap in 2–4 is smaller than in the corresponding cyclopentadienyl complexes 2-Cp–4-Cp (e.g. 5.47 (2) vs. 6.31 eV (2-Cp)). In order to assess the stability of 2–4, particularly the ruthenium–dicarbollide bond, energy decomposition analysis (EDA) of 2–4, together with the respective cyclopentadienyl analogues 2-Cp–4-Cp, was performed. EDA suggests that the ruthenium(II)–dicarbollide bond in the three complexes is mostly ionic and far stronger than the ruthenium(II)–arene bond.

中文翻译：

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（η的抗增殖活性⁶对HCT116和MCF7细胞系-arene）ruthenacarborane夹心复合

三[（η ⁶ -arene）RUC ₂乙₉ ħ ₁₁ ]配合物（芳烃= p -cymene（2），联苯（3）和1-ME-4-COOEt烷基-C ₆ H ^ ₄（4））根据合成修改文献程序并充分表征。发现2–4对两种类型的肿瘤细胞系（HCT116和MCF7）具有中等活性，IC ₅₀值在低微摩尔范围内。但是，正常，健康细胞（MRC-5细胞系，MLEC和小鼠巨噬细胞）的存活率不受2-4处理的影响与非选择性抗肿瘤药顺铂和其他潜在的Ru ^II药物相比，表明金属碳硼烷复合物对肿瘤细胞系具有高选择性。此外，流式细胞仪分析表明4通过caspase依赖性凋亡机制诱导细胞死亡。前沿分子轨道的DFT计算表明，2-4中的HOMO-LUMO间隙小于相应的环戊二烯基络合物2-Cp-4-Cp（例如5.47（2）对6.31 eV（2-Cp））。为了评估2–4的稳定性尤其是钌-二糖脂键，2-4的能量分解分析（EDA）以及各自的环戊二烯基类似物2-Cp-4-Cp。EDA表明钌（II）-dicarbollide在三个复合物键主要是离子的和远低于钌（更强II）-arene键。