Co-ordination chemistry of higher oxidation states. Part 1. Thioether complexes of osmium (IV), iridium(IV), and platinum(IV)

Abstract

Osmium(IV) dithioether complexes [OsLCl₄][L = RS(CH₂)₂SR, RSCHCHSR, or o-C₆H₄(SR)₂; R = Me or Ph] have been prepared from the ligands and sodium hexachloro-osmate(IV); [OsL′Br₄](L′= MeS(CH₂)₂SMe or MeSCHCHSMe) are formed from K₂[OsBr₆]. Iridium(III) anions, [NMe₄][IrLCl₄], cis- and trans-[Ir(SMe₂)₂Cl₄]^–, [Ir(SPh₂)₂Cl₄]^–, and [Ir(SPh₂)Cl₅]^2–, are oxidized by chlorine to the corresponding iridium(IV) complexes. Halogen oxidation of [PtLX₂] produces [PtLX₄](X = Cl or Br) and two unstable complexes [PtL″l₄][L″= MeS(CH₂)_nSMe, n= 2 or 3]. Attempts to prepare thioether complexes of Ru^IV, Rh^IV, Pd^IV, Co^III, and Ni^III have been unsuccessful. The isolated complexes have been characterized by i.r. and electronic spectroscopy, and where appropriate magnetic measurements and ¹H n.m.r. spectroscopy. Variable-temperature ¹H n.m.r. spectra show that inversion at sulphur co-ordinated to Pt^IV is more difficult than in the platinum(II) analogues. Thermal decomposition of [PtLX₄](X = Cl, Br, or I) involves both dehalogenation and dealkylation.