Hydrogen–deuterium exchange at a saturated carbon atom in tertiary phosphine complexes of platinum(II)

Abstract

Chloro-bridged diplatinum(II) complexes of the type [Pt2Cl4L2](L = PPr3, PBu3, PButPr2, PBut2Pr, PPrPh2, PPr2Ph, or PButPh2), undergo a regiospecific hydrogen-deuterium exchange in an aqueous (D2O) acetic acid (CH3CO2D) medium to give complexes containing deuterium in the alkyl groups of the tertiary phosphine moiety and, in the case of L = PButPh2, also in the aryl groups. The steric requirements of the tertiary phosphine have a marked influence on both the rate and the position of deuterium incorporation. The results presented show that, in internal-metallation reactions of platinum, the ease of ring formation decreases in the order five-membered > six-membered > four-membered rings. It is suggested that in such reactions steric rather than electronic factors are dominant.