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Ionic platinum(II) complexes [PtCl(PPh 3 )(L∧L)][BF 4 ] {L∧L = 2,2′-bipyridyl ( 1 ) 1,10-phenanthroline ( 2 )} and [PtCl(PPh 3 )(L) 2 ][BF 4 ] {L = pyridine ( 3 ), dimethyl sulfoxide ( 4 )} were synthesized by dehalogenation of cis- [PtCl 2 (PPh 3 )(NCMe)], followed by reaction with the suitable ligand. Chelating nitrogen ligands L∧L afforded single products, which were structurally characterized. In the other cases mixtures of geometric (L = pyridine) and/or coordination (L = dimethyl sulfoxide) isomers were observed in solution. In these cases the structures of the less soluble isomers were obtained via single crystal X-ray diffraction. All the complexes were tested in vitro for their antiproliferative activity on three human tumor cell lines: MSTO-211H, HeLa and HepG2. [ABSTRACT FROM AUTHOR]

Dinuclear platinum(II) complexes [{PtCl 2 (PPh 3 )} 2 (μ-N–N)], where N–N is a divergent bidentate nitrogen ligand, were prepared by reacting cis -[PtCl 2 (PPh 3 )(NCMe)] with N–N in a Pt/N–N molar ratio 2. The ( trans , trans )-isomers were obtained as kinetic products and recovered in good yields and high purity { 1 , N–N = pyrazine (pyrz); 2 , N–N = 4,4′-bipyridyl (bipy); 3 , N–N = piperazine (pipz); 4 , N–N = p-xylylendiamine (xylN 2 )}. Cis -[PtCl 2 (PPh 3 )(NCMe)] was also reacted with the tridentate divergent ligand 2,4,6-tris-(pyrid-4′-yl)1,3,5-triazine (py3TRIA) in molar ratio 3 with formation of the trinuclear ( trans , trans , trans )-[{PtCl 2 (PPh 3 )} 3 (μ-py3TRIA)], 5 . On the other hand, the treatment of cis -[PtCl 2 (PPh 3 )(NCMe)] with the monodentate pyridine (py) produced a mixture of both trans -[PtCl 2 (PPh 3 )(py)] ( 6a ) and cis -[PtCl 2 (PPh 3 )(py)] ( 6b ). The reactions of cis -[PtCl 2 (PPh 3 )(NCMe)] with N–N = pyrz, bipy, pipz, carried out with a Pt/N–N molar ratio 1, were monitored by 31 P NMR spectroscopy. Equilibria were observed in solution, involving dinuclear ( trans – trans )-[{PtCl 2 (PPh 3 )} 2 (μ-N–N)], mononuclear [PtCl 2 (PPh 3 )(N–N)] and free N–N. The addition of an excess of the divergent ligand allowed the complete conversion to the corresponding mononuclear complexes. With the heteroaromatic ligands both geometric isomers were observed ( 7a , 7b and 8a , 8b , for pyrz and bipy derivatives, respectively) while with pipz the trans -isomer only was detected, 9 . In the system involving bipy, the scarcely soluble dinuclear ( cis , cis )-[{PtCl 2 (PPh 3 )} 2 (μ-bipy)], 2b , was also obtained. Products 2 , 2b , 3 ·2(CHCl 3 ) and 6a ·0.5(C 2 H 4 Cl 2 ) were structurally characterized by single crystal X-ray diffraction methods. [ABSTRACT FROM AUTHOR]