Systematics of palladium(II) and platinum(II) dithioether complexes. The effect of ligand structure upon the structure and spectra of the complexes and upon inversion at coordinated sulphur

Abstract

Planar complexes cis-[MLX 2] (M = Pd, Pt; X = Cl, Br, I) and [ML 2(ClO 4) 2 have been prepared for the dithioethers (L), MeS(CH 2) nSMe (n = 2, 3), PhS(CH 2) nSPh (n = 2, 3), cis-RSCH=CHSR (R = Me, Ph) and o-C 6H 4(SR) 2 (R = Me, Ph). The ligands PhS(CH 2) nSPh (n = 6, 8) yield polymeric [PdLX 2] n, whilst PhS(CH 2) 12SPh produces the trans chelates, trans-[PdLX 2] (X = Cl, Br) and trans-[PtLCl 2]. The infrared, uv-visible (both solid state and solution) and 1H spectra are reported and discussed. The [ML 2](ClO 4) 2 complexes are 1:2 electrolytes but several show evidence for ion association. The 1H nmr spectra are reported for the complexes of the methyl substituted ligands and the coordination shifts of the methyl and vinyl protons and 3J PtH coupling are discussed. The variable temperature 1H nmr spectra show that rate of inversion at coordinated sulphur lies in the order Pt <Pd and Cl < I. Variation with backbone gives the order -CH 2CH 2- < o-C 6H 4 < cis-CHCH- < -CH 2CH 2CH 2-.