Study of the aqueous reactions of K[Pt(Ph2SO)Cl3] with nitrile ligands and crystal structures of N(C4H9)4[Pt(Ph2SO)Cl3], N(C2H5)4[Pt(Ph2SO)Br3] and cis-Pt(Ph2SO)(C3H5CN)Cl2

The aqeuous reactions of K[Pt(Ph2So)Cl1] with nitriles were studied in different conditions of pH, mainly by 195Pt and 1H NMR. At normal pH (≈ 2.4), the ligands RCN have produced the neutral complexes Pt(Ph2SO)(RCN)Cl2. For acetonitrile, only the cis isomer was obtained, while for other nitriles a mixture of the two isomers was formed. The 195Pt NMR spectra of the compounds were measured. The signals of the cis isomers were observed around −3040 ppm, while those of the trans isomers were found around − 3180 ppm. The study has shown that the first product formed is the trans isomer, which then isomerizes partially to the cis compounds. The 195Pt NMR spectra of the products obtained in neutral medium (pH adjusted to ∼ 7 with NaOH) have shown several signals depending on the nitrile. Dimeric species of the type Pt(Ph2SO)Cl(μ-NHC(R)O2Pt(Ph2SO)Cl are suggested to exist in solution. Head-to-head and head-to-tail isomers are probably formed. The crystal structures of N(C4H9)4[Pt(Ph2SO)Cl3] (I), N(C2H5)4[Pt(Ph2SO)Br3] (II) and cis-Pt(Ph2SO)(C3H5CN)Cl2 (III) were determined. The chloro ionic complex is triclinic, P-1, with a = 10.674(2), b = 11.424(2), c = 13.731(2) Å, α = 89.54(1), β = 83.27(1), γ = 80.48(1)°, Z = 2 rmand R = 0.042, while the bromo complex is monoclinic, P21/n, with a = 11.258(3), b = 19.425(4), c = 11.590(2) Å, β = 102.62(2)°, Z = 4 and R = 0.053. Crystal III is orthorhombic, space group P212121, a = 9.532(3), b = 11.787(2), c = 15.464(4) Å, Z = 4 and R = 0.031. The compound is the cis isomer. For crystal I, the PtCl bond in trans position to the sulfoxide is 2.312(2) Å, while the cis bonds are 2.282(2) and 2.299(2) Å. For the bromo compound (II), the PtBr bonds vary between 2.397(3) and 2.421(3) Å. In crystal III, the PtCl bond located in trans position to the nitrile is considerably shorter (2.269(3) Å) than the PtCl bond in trans position to the sulfoxide ligand (2.311(3) Å). The PtS bond distances vary between 2.201(2) and 2.228(3) Å.