Synthesis of thecis andtrans isomers oftert-butylaminedichloro-(dimethyl sulphoxide)platinum(II) and X-ray structure analysis of thecis compound

Abstract

Treatment ofcis-dichlorobis(dimethyl sulphoxide)platinum(II) [1] with an excess oftert-butylamine in MeOH yieldstert-butylamine-trans-dichloro(dimethyl sulphoxide)-platinum(II) [(tr-5)], rather than thecis-diaminechloro-(dimethyl sulphoxide)platinum(II) cation expected by analogy with similar reactions reported in the literature. The correspondingcis isomer [(cis-5)] is prepared from the same reactants (and similarly from K2PtCl4 andtert-butylamine) in DMSO medium, in which the initially formedtrans compound partially isomerizes to the thermodynamically favouredcis complex. The molecular structure of (cis-5) is determined by X-ray analysis. The coordination around the Pt atom is square-planar, and the DMSO ligand is S-coordinated. The lengths of the Pt-Cl bondscis andtrans to the DMSO ligand are 2.296(11) and 2.321(10) A, respectively, and are well within expected ranges. Interatomic distances within the amine and DMSO ligands are normal.