Ligands containing elements of Group VB. Part II. Silver complexes of substituted bis(carboxymethyl)phenylarsines

Abstract

The preparation of a range of substituted bis(carboxymethyl)phenylarsines of general formula R·C₆H₄·As(CH₂·CO₂H)₂(H₂L) is described and their acid dissociation constants measured at 20° and µ= 0·10M(KNO₃). It was considered that the complex species AgL^–, AgHL, and AgH₂L⁺ only were formed, and their formation constants, under the same conditions, have been calculated by measuring pH and pAg simultaneously during titrations of mixtures of the ligand and silver ions with alkali. Values for the formation constants are related to one another through the Hammett σ values for their substituents and the results interpreted as providing no evidence for back co-ordination.