Reactions of [Pt(dien)Cl]Cl and [Pt(trpy)Cl]Cl with thiols, thioethers, and dialkyl disulfides: A [sup 195]Pt NMR study

The reactions of monofunctional platinum compounds [Pt(dien)Cl]Cl (dien = 1,5-diamino-3-azapentane) and [Pt(trpy)Cl]Cl (trpy = 2,2[prime],2[double prime]-terpyridine) with thiols (RSH), thioethers (RSR), and disulfides (RSSR) have been investigated by [sup 1]H, [sup 13]C, and [sup 195]Pt NMR spectroscopy. Empirical trends in [sup 195]Pt NMR chemical shifts are noted in terms of the classes sulfur functional groups coordinated to platinum. It appears that neither the steric bulk nor the electronic character of the alkyl group makes a significant contribution to the [sup 195]Pt nuclear shielding. Reactions of dialkyl disulfides with [Pt(dien)Cl]Cl initially lead to a monodentate complex [Pt(dien)(RSSR)][sup 2+] which can be isolated as the ClO[sub 4][sup [minus]] or PF[sub 6][sup [minus]] salts. In the presence of [Pt(dien)Cl]Cl, the monodentate disulfido complex undergoes further reaction to cleave the S-S bond in the disulfide ligand, via a redox process.