Mode of binding of dimethyl sulphoxide in platinum(II) and palladium(II) cationic complexes containing a chelated diamine. X-Ray crystal structures of (2,2′-bipyridyl)chloro(dimethyl sulphoxide-O)palladium(II) tetrafluoroborate and chloro(dimethyl sulphoxide-S)(ethylenediamine)palladium(II) perchlorate

The mode of binding of dimethyl sulphoxide (dmso) in cations of the type [M(N-N)(dmso)Cl]⁺ [M = Pd or Pt; N-N = 2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen), or ethylenediamine (en)] has been examined by i.r. and ¹H n.m.r. spectroscopy. Infrared spectra of the complexes in the solid state indicate that dmso binds through oxygen in the palladium(II) adducts containing bipy and phen, and through sulphur in the other cases. Proton n.m.r. spectra in CD<inf>3</inf>NO<inf>2</inf> solution show that the complexes in which dmso is S-bonded in the solid state retain their structure in solution, while those containing O-bonded dmso equilibrate to a mixture of O- and S-bonded isomers whose composition depends upon the nature of the chelated diamine. Interconversion between the two isomers is slow on the n.m.r. time-scale, while exchange of S- and O-bonded dmso is fast. The crystal and molecular structures of [Pd(bipy)(dmso)Cl] [BF<inf>4</inf>], (1), and [Pd(en)(dmso)Cl]...