PLATINUM(II) AND PALLADIUM(II) COMPLEXES WITH 2-AMINO-4-METHYLSULFANYLBUTANOL AND 2-(ETHYLSULFANYL)ETHYLAMINE

The reaction of K2[PtX4] (X = Cl or Br) with 2-(ethylsulfanyl)ethylami ne (esea) (molar ratio 1:1) in aqueous solution yielded ionic [Pt(esea )2][PtX4] complexes which undergo thermal rearrangement to [PtX2(esea) ]. By treating [PtCl2(esea)] or [PtX2(ambo)] (ambo = L-2-amino-4-methy lsulfanylbutanol; X = Cl or Br) with an excess of the corresponding [P tX4]2- in water the binuclear complexes K[Pt2Cl5(esea)] and K[Pt2X5(am bo)] have been obtained. The crystal structure of K[Pt2Cl5(ambo)] was determined by X-ray crystallography and refined to R = 0.034, based on 1685 observed reflections. This binuclear complex, in which the ambo ligand is chelated to Pt(1) through the N and S donor atoms and also c o-ordinated to Pt(2) through the S atom, is the first example of a che lated methionine derivative with S acting as bridging donor. The Pt at oms are four-co-ordinate in a slightly distorted square-planar geometr y. Selected bond distances are Pt-Cl 2.30 (mean of five values), Pt-S 2.26 (mean), and Pt-N 2.05(1) angstrom; the Pt(1)-S-Pt(2) angle is 116 .8(2)-degrees. Proton NMR spectra support rupture of the sulfur bridge of the binuclear complexes in dimethyl sulfoxide to form the correspo nding [PtX2L] species. The presence of equilibria between ionic and ne utral species in the same solvent is also discussed.