1-AMINO-4-ARYL-2(1H)-PYRIMIDINETHIONES - ACIDITY AND COMPLEX-FORMATION WITH NONFERROUS METAL-IONS AND AG(I)

Acid dissociation constants of new 2, 3 and already known 1 substituted 1-amino-4-aryl-2(1H)-pyrimidinethiones and stability constants of their nonferrous metal ion and silver complexes have been measured ph-potentiometrically in a 75 % (v/v) mixture of dioxane/water. The influence of the substituents on pK(a)- and Igbeta(n)-values is discussed. The X-ray structure analysis of bis[1-(4-toluenesulfonamido)-4-(4-tolyl)-2(1H)-pyrimidinethionatol]-nickel(II) 5 proves that pyrimidinethiones coordinate via their thione sulphur and amino-nitrogen. However, the bond lengths are not levelled in the chelating ring.