Metallkomplexe mit biologisch wichtigen Liganden

A Comparative Analysis of the In Vitro Anticancer Activity of Iridium(III) {η5-C5Me4R} Complexes with Variable R Groups

Piano-stool iridium complexes based on the pentamethylcyclopentadienyl ligand (Cp*) have been intensively investigated as anticancer drug candidates and hold much promise in this setting. A systematic study aimed at outlining the effect of Cp* mono-derivatization on the antiproliferative activity is presented here. Thus, the dinuclear complexes [Ir(η⁵-C₅Me₄R)Cl(μ-Cl)]₂ (R = Me, 1a; R = H, 1b; R = Pr, 1c; R = 4-C₆H₄F, 1d; R = 4-C₆H₄OH, 1e), their 2-phenylpyridyl mononuclear derivatives [Ir(η⁵-C₅Me₄R)(k_N,k_CPhPy)Cl] (2a-d), and the dimethylsulfoxide complex [Ir{η⁵-C₅Me₄(4-C₆H₄OH)}Cl₂(κ_S-Me₂S=O)] (3) were synthesized, structurally characterized, and assessed for their cytotoxicity towards a panel of six human and rodent cancer cell lines (mouse melanoma, B16; rat glioma, C6; breast adenocarcinoma, MCF-7; colorectal carcinoma, SW620 and HCT116; ovarian carcinoma, A2780) and one primary, human fetal lung fibroblast cell line (MRC5). Complexes 2b (R = H) and 2d (4-C₆H₄F) emerged as the most active ones and were selected for further investigation. They did not affect the viability of primary mouse peritoneal cells, and their tumoricidal action arises from the combined influence on cellular proliferation, apoptosis and senescence. The latter is triggered by mitochondrial failure and production of reactive oxygen and nitrogen species.

Ru(ii)–thyminate complexes: new metallodrug candidates against tumor cells

Herein, we used thymine (HThy) as a ligand to form two new ruthenium(ii) complexes with formula [Ru(PPh₃)₂(Thy)(bipy)]PF₆ (1) and [Ru(Thy)(bipy)(dppb)]PF₆ (2).

Crystal structures of bis-[2-(pyridin-2-yl)phenyl-κ(2) N,C (1)]rhodium(III) complexes containing an aceto-nitrile or monodentate thyminate(1-) ligand

The crystal structures of bis-[2-(pyridin-2-yl)phen-yl]rhodium(III) complexes with the metal in an octahedral coordination containing chloride and aceto-nitrile ligands, namely (OC-6-42)-aceto-nitrile-chlorido-bis-[2-(pyridin-2-yl)phenyl-κ(2) N,C (1)]rhodium(III), [RhCl(C11H8N)2(CH3CN)] (1), thyminate(1-) and methanol, namely (OC-6-42)-methanol(5-methyl-2,4-dioxo-1,2,3,4-tetrahydro-pyrimidin-1-ido-κN (1))bis-[2-(pyridin-2-yl)phenyl-κ(2) N,C (1)]rhodium(III), [Rh(C11H8N)2(C5H5N2O2)(CH3OH)]·CH3OH·0.5H2O (2), and thy-min-ate(1-) and ethanol, namely (OC-6-42)-ethanol(5-methyl-2,4-dioxo-1,2,3,4-tetra-hydro-pyrimidin-1-ido-κN (1))bis[2-(pyridin-2-yl)phenyl-κ(2) N,C (1)]rhodium(III), [Rh(C11H8N)2(C5H5N2O2)(C2H5OH)]·C2H5OH (3), are reported. The aceto-nitrile complex, 1, is isostructural with the Ir(III) analog. In complexes 2 and 3, the monodeprotonated thyminate (Hthym(-)) ligand coordinates to the Rh(III) atom through the N atom, and the resulting Rh-N(Hthym) bond lengths are relatively long [2.261 (2) and 2.252 (2) Å for 2 and 3, respectively] as compared to the Rh-N bonds in the related thyminate complexes. In each of the crystals of 2 and 3, the complexes are linked via a pair of inter-molecular N-H⋯O hydrogen bonds between neighbouring Hthym(-) ligands, forming an inversion dimer. A strong intra-molecular O-H⋯O hydrogen bond between the thyminate(1-) and alcohol ligands in mutually cis positions to each other is also observed.

Rhodium(III) and Iridium(III) Solvates of the Form [(eta(5)-C(5)Me(5))M(S)(3)](2+) as Models for the Reactivity of Half-Sandwich Compounds(1)

Solvent exchange on the half-sandwich organic solvates [(eta(5)-C(5)Me(5))M(S)(3)](2+) (M = Rh, S = MeCN (1) or Me(2)SO (3); and M = Ir, S = MeCN (2) or Me(2)SO (4)) has been investigated as a function of temperature, pressure, and concentration of free solvent by (1)H NMR line-broadening techniques in CD(3)CN and/or CD(3)NO(2). The exchange rates span several orders of magnitude, from k(ex)(298) = 8.8 x 10(-)(2) s(-)(1) for 2 to 3.6 x 10(3) s(-)(1) for 3, as a result of changes in the electronic and steric properties of the ligands. Nevertheless, the volume of activation remains consistently positive for compounds 1-4 with values ranging from +0.8 to +3.3 cm(3) mol(-)(1). In combination with the positive activation entropies obtained and the first-order rate law established for these systems, it was concluded that regardless of the nature of the ligand the solvent exchange process on 1-4 proceeds via a dissociative D mechanism. Of note, the intermolecular exchange with free Me(2)SO on 4 takes place exclusively from a conformational isomer of 4 (structure 4.2), which is itself in equilibrium with a second, more compact conformer (structure 4.1).