ESTABLISHMENT OF RELATIONS BETWEEN COMPLEX STABILITY AND PHOSPHATE GROUP BASICITY FOR THE COPPER(II) COMPLEXES OF SIMPLE PHOSPHATE MONOESTERS IN DIOXANE-WATER MIXTURES

The acidity constants of H(R-MP)-, where R-MP2-=4-nitrophenyl phosphat e (NPhp2-), phenyl phosphate (PhP2-), D-ribose 5'-monophosphate (RibMP 2-), and n-butyl phosphate (BuP2-) and the stability constants of the corresponding binary Cu(R-MP) complexes were collected for aqueous sol ution and for 20, 30, 40 and 50% (v/v) 1,4-dioxane-water mixtures (I = 0.1 M, NaNO3; 25-degrees). For each solvent log K(cu(R-MP))cu versus pK(H(R-MP))H plots were constructed; in all cases straight lines are o btained. The corresponding straight-line equations (determined via a l east-squares procedure) together with the pK(a) value of a given phosp hate group allow now to predict the stability of the corresponding Cu( R-MP) complex in the considered solvent.