Chiral and achiral platinum(II) complexes for potential use as chemotherapeutic agents: crystal and molecular structures of cis-[Pt(L-1)(2)] and [Pt(L-1)Cl(MPSO)] [HL1 = N,N-diethyl-N'-benzoylthiourea]

The synthesis and characterisation of platinum(II) complexes, with the gene ral formula [Pt(acylthioureato)Cl(RR'SO)], is reported. These complexes are readily formed by the reaction of [PtCl2(RR'SO)(2)] with the acylthiourea ligands, N,N-di(2-hydroxyethyl)-N'-benzoylthiourea (HL), N'-benzoylthiourea (HL1) and N,N-adipoylbis(N',N'-diethylthiourea) (H2L2) in the presence of sodium acetate. Variation of the sulfoxide ligand (RR'SO) enables preparati on of achiral complexes when RR'SO is dimethylsulfoxide (DMSO) or methylphe nylsulfoxide (MPSO), and chiral complexes when use is made of the chiral su lfoxides, such as (R)-methyl(p-tolyl)sulfoxide and (S)-methyl(p-tolyl)sulfo xide. The reaction also yields, as a minor product, the corresponding cis-b is(acylthioureato)platinum(II) complexes, which can be removed by chromatog raphy. The molecular structures of the two products, [Pt(L-1)Cl(MPSO)] and cis-[Pt(L-1)(2)], were determined by X-ray crystallography. The sulfoxide o f [Pt(L-1)Cl(MPSO)] is sulfur bound, as expected, and cis to the sulfur ato m of the acylthioureato ligand. All bond lengths and bond angles around the square planar platinum are normal, with the Pt-S bond trans to Cl being 2. 257(4) Angstrom and the Pt-S bond trans to O 2.192(3) Angstrom in length. T he Pt-O and Pt-Cl bonds are 2.016(9) and 2.334(3) Angstrom, respectively, a nd are within the expected ranges. Similarly, the bond lengths and bond ang les around the coordination plane of cis-[Pt(L-1)(2)] compare well with rel ated complexes.