Bifunctional derivatives of the chelating agents ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, in which a p-isothiocyanatobenzyl moiety is attached at the methylene carbon atom of one carboxymethyl arm, was synthesized by reductive alkylation of the relevant polyamine with (pnitropheny1) pyruvic acid followed by carboxymethylation, reduction of the nitro group, and reaction with thiophosgene. The ...