Ruthenium(II)-arene complexes with functionalized pyridines: synthesis, characterization and cytotoxic activity.

Ruthenium(II)-arene complexes of general formulae [(eta(6)-p-cymene)Ru(L(1-3))Cl(2)], where L(1-3) is 3-acetylpyridine (1), 4-acetylpyridine (2) and 2-amino-5-chloropyridine (3), correspondingly, [(eta(6)-p-cymene)Ru(HL(4,5))Cl(2)], where HL(4) and HL(5) are respectively isonicotinic acid (4) and nicotinic acid (5) and [(eta(6)-p-cymene)Ru(HL(6-9))Cl], where H(2)L(6-9) represent 2,3-pyridinedicarboxylic acid (6), 2,4-pyridinedicarboxylic acid (7), 2,5-pyridinedicarboxylic acid (8) and 2,6-pyridinedicarboxylic acid (9), were prepared by the reaction of (eta(6)-p-cymene)(2)RuCl(2) (10) with the corresponding ligand in 1:2 molar ratio in isopropanol. The complexes were characterized by elemental analysis, mass spectrometry, IR and NMR spectroscopies. According to these data the molecules adopt the usual "three-leg piano-stool" geometry which is common for this type of complexes. The structures of 1 and 7 were determined by X-ray crystallography. The complexes revealed low antiproliferative activity in six investigated tumor cell lines (HeLa, B16, FemX, MDA-MB-361, MDA-MB-453 and LS-174). The reaction of 6 with 9-methyladenine was studied by (1)H NMR, (1)H, (1)H COSY and (1)H, (1)H NOESY spectroscopy.