Metal and Substituent Influence on the Cytostatic Activity of Cationic Bis-cyclometallated Iridium and Rhodium Complexes with Substituted 1,10-Phenanthrolines as Ancillary Ligands: Metal and Substituent Influence on the Cytostatic Activity of Cationic Bis-cyclometallated Iridium and Rhodium Complexes with Substituted 1,10-Phenant

Synthesis and characterization of the new cyclometalated complex salts [Rh(ptpy)2(5.6‐dimethyl‐1,10‐phenanthroline)]PF6 (1a) [Rh(ptpy)2(2.9‐dimethyl‐4.7‐diphenyl‐1,10‐ phenanthroline)]PF6 (2a), [Rh(ptpy)2(5‐amino‐1,10‐phenanthroline)] PF6 (3a), and [M(ptpy)2 (pyrazino‐[2.3‐f]‐1,10‐phenanthroline)]PF6 (M = Rh, 4a; M = Ir, 4b), (ptpy = 2‐(p‐tolyl)pyridinato) are described. The molecular structures of compounds 1b and 4a in the solid state were determined by single‐crystal X‐ray diffraction. All these compounds and their already known Iridium counterparts 1b – 3b display significant cytotoxicity against human cancer cell lines MCF‐7 (human breast adenocarcinoma) and HT‐29 (colon adenocarcinoma) with IC50 values in the low micromolar range.