Acid-base equilibria of the aqua adducts of Ru(II) arene complexes with functionalised pyridines

Abstract

Acid-base equilibria of the aqua adducts of Ru(II) arene complexes, general formulae [(eta(6)-p-cymene)Ru (L1-3)Cl-2] where L-1 = 3-acetylpyridine (1), L-2 = 4-acetylpyridine (2) and L-3 = 2-amino-5-chloropyridine (3), then [(eta(6)-p-cymene)Ru(HL4)Cl-2] with HL4 = isonicotinic acid (4); [(eta(6)-p-cymene)Ru(HL5-8)Cl] where H2L5 = 2,3-pyridine dicarboxylic acid (5), H2L6 = 2,4-pyridine dicarboxylic acid (6), H2L7 = 2,5-pyridine dicarboxylic acid (7) and H2L8 = 2,6-pyridine dicarboxylic acid (8) have been studied. pK (a) values were determined by potentiometry at 25 A degrees C and constant ionic strength of 0.1 M NaNO3. The assumed equilibria were confirmed by UV and H-1-NMR spectroscopy.