Studies on the reactions of dihydrogen with salts of platinum carbonyl cluster anions (Chini clusters) and redox active countercations

Abstract

Reactions of A(n)[Pt-12(CO)(24)] (A methylene blue (MB+), safranine O (Saf(+)), nicotinamide benzyl chloride (BNA(+)), n = 2; A methylviologen (MV2+), n = 1) with dihydrogen in DMF and DMSO have been studied. Spectroscopic (NMR, ESR, and UV-vis) monitoring shows selective and total reduction of MB+, Saf(+), and MV2+ to MBH, SafH, and MV+ respectively, accompanied by conversion of [Pt-12(CO)(24)](2-) to [Pt-9(CO)(18)](2-). No BNAH (analogue and model for NADH) is formed in the reaction of [BNA](2)[Pt-12(CO)(24)] with dihydrogen. However, in the reactions of BNA(+)Cl(-), [Saf](2)[Pt-12(CO)(24)], and dihydrogen, BNAH is formed in small quantities in DMSO and quantitatively in a biphasic system (water and dichloromethane). The redox behaviors of MB+, Saf(+), MV2+, and BNA(+) as chloride salts have also been studied in DMF by cyclic voltammetry, and the data have been used to rationalize some of the observed reactions. The dihydrogen-driven, [Bu4N](2)[Pt-12(CO)(24)]-catalyzed transport of A(+) (A(divided by) = MB+, Saf(+)) as AH through a liquid membrane has also been studied.