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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. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of four compounds [M(η5‐C5Me5)(N^N)Cl]PF6 [N^N=4,7‐dichloro‐1,10‐phenanthroline with M=Rh, 1, and M=Ir, 2, and N^N=4'‐(4‐chlorophenyl)‐2,2':6',2''‐terpyridine in the κ2N,N'‐coordination mode with M=Rh, 3, and M=Ir, 4] are described. All compounds were characterized by spectroscopic means and their molecular structures in the crystal were confirmed by single‐crystal X‐ray diffraction studies. The cytotoxicity of all compounds was evaluated by MTT assay against the three cancer cell lines HeLa (cervical carcinoma), HT‐29 (colon adenocarcinoma) and MCF‐7 (human breast adenocarcinoma). The complexes 3 and 4 display promising activity with IC50 values of 1 μM. The rhodium(III) complex 1 also shows highly improved cytotoxicity compared to cisplatin against the cancer cell lines HT‐29 and MCF‐7. In contrast to this, the iridium(III) complex 2 is even less active against the HeLa cell line than cisplatin. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of two new bis‐cyclometalated compounds [Ir(ptpy)2(κ2N‐terpy‐C6H4Cl‐p)]PF6 [terpy‐C6H4Cl‐p=4'‐(4‐chlorophenyl)‐2,2':6',2"‐terpyridine, (1)], and [Ir(ptpy)2(κ2N‐terpy‐Cl)]PF6 [terpy‐Cl=4'‐chloro‐2,2':6',2''‐terpyridine, (2); ptpy=2‐(p‐tolyl)pyridinato)] are described. The molecular structures of compounds 1 and 2 in the crystal were determined by single‐crystal X‐ray diffraction. 1 crystallized from dichloromethane/methanol/iso‐hexane in the monoclinic space group P2/n and 2 from the same mixture of solvents in the triclinic space group P−1. Photophysical investigations on 1 and 2 revealed broad unstructured luminescence in the red spectral region with the emission maxima in dichloromethane at 620 and 630 nm respectively. To explore cytotoxic properties of compounds 1 and 2, a colorimetric assay (MTT assay) against prominent cancer cell lines, MCF‐7 and HT‐29, was performed. The determined IC50 values are in the low micromolar range (2–3 μM). In comparison to cisplatin, the tested complexes 1 and 2 exhibit up to >20‐fold (MCF‐7) and >40‐fold (HT‐29) increase in biological activity. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of new bis‐cyclometalated complex salts [Ir(ptpy)2(Lphen)]PF6 with Lphen = 2,9‐dimethyl‐4,7‐bis(pentyloxy)‐1,10‐phenanthroline (1) and Lphen = 2,9‐dimethyl‐4,7‐bis(2‐ethoxyethoxyl)‐1,10‐phenanthroline (2) are described. Compounds 1 and 2 were obtained by the reaction of the corresponding phenanthroline ligands with [{Ir(μ‐Cl)(ptpy)2}2] in a refluxing CH2Cl2/MeOH mixture. The molecular structure of compound 2 was confirmed by single‐crystal X‐ray structure determination. Complex 2 was crystallized from dichloromethane/methanol/iso‐hexane in the monoclinic space group P21/c. The biological activity of both new compounds was examined, and they exhibit significant cytotoxicity against human cancer cell lines with the IC50 values around 2 μM, significantly better than the established anticancer drug cisplatin under identical conditions. [ABSTRACT FROM AUTHOR]

The synthesis of [Rh2(η5‐Cp)2(μ‐H)(μ‐PPh2)2]BF4 (2) by protonation reaction of the metal basic complex [Rh2(η5‐Cp)2(μ‐PPh2)2] (1) with tetrafluoroboric acid in diethyl ether is described. Complex salt 2 was obtained in high yield and fully characterized by spectroscopic means and X‐ray crystal diffraction. Applying the isolobal analogy between H and the fragment Au(PPh3) as a synthetic strategy on the reaction of compound 2 with equimolar amounts of [Au(CH3)(PPh3)] in refluxing acetone resulted in the formation of the expected triangular cluster compound [Rh2{μ‐Au(PPh3)}(η5‐Cp)2(μ‐PPh2)2]BF4 (3) in good yield. Metal cluster salt 3 was fully characterized by spectroscopic data and its molecular structure in the crystal was determined by X‐ray diffraction. The structural comparison of the protonated dirhodium core in the cationic complex of 2 with the Rh2Au framework in 3 is in good accordance with the isolobal relation between H+ and Au+ because they share the respective same position in these closely related molecular structures. [ABSTRACT FROM AUTHOR]

The reaction of equimolar amounts of [Co(CO)3(NO)] and [PPN]CN, PPN+ = (PPh3)2N+, in THF at room temperature resulted in ligand substitution of a carbonyl towards the cyanido ligand presumably affording the complex salt PPN[Co(CO)2(NO)(CN)] as a reactive intermediate species which could not be isolated. Applying the synthetic protocol using the nitrosyl carbonyl in excess, the title reaction afforded unexpectedly the novel complex salt PPN[Co2(μ‐CN)(CO)4(NO)2] (1) in high yield. Because of many disorder phenomena in crystals of 1 the corresponding NBu4+ salt of 1 has been prepared and the molecular structure of the dinuclear metal core in NnBu4[Co2(μ‐CN)(CO)4(NO)2] (2) was determined by X‐ray crystal diffraction in a more satisfactory manner. In contrast to the former result, the reaction of [PPN]SCN with [Co(CO)3(NO)] yielded the mononuclear complex salt PPN[Co(CO)2(NO)(SCN‐κN)] (3) in good yield whose molecular structure in the solid was even determined and its composition additionally confirmed by spectroscopic means. [ABSTRACT FROM AUTHOR]

The reaction of [Ru3(CO)12] with P(o‐tolyl)2H (molar ratio of 1 to 2) in refluxing THF afforded the electron‐precise metal cluster [Ru3(μ‐H)2(μ‐P{o‐tolyl}2)2(CO)8] (3). This reaction behavior is comparable to that using the secondary phosphane PtBu2H operating with the same molar ratio. As shown in earlier work, the ruthenium carbonyl reacted with an excess of PtBu2H under similar conditions with cluster degradation affording the coordinatively unsaturated complex [Ru2(μ‐H)(μ‐PtBu2)(PtBu2H)2(CO)4]. We found that the reaction using similar reaction conditions with P(o‐tolyl)2H in excess did not result in such a reactive dinuclear species. Here compound 3 was formed in a first step, which reacted with excess of the phosphane affording the new cluster [Ru3(μ‐H)2(μ‐P{o‐tolyl}2)2(P{o‐tolyl}2H)2(CO)6] (2). The molecular structures of 2 and 3 in the solid were confirmed by single‐crystal X‐ray analysis. Moreover, the 31P NMR spectra of the new compounds showed coalescence phenomena on the NMR time scale caused by a restricted rotation about the P–C bonds, and, presumably, about Ru–P bonds, within the phosphane and phosphanido ligands. [ABSTRACT FROM AUTHOR]