STUDY OF THE AQUEOUS REACTIONS OF K[PT(PH2SO)CL-3] WITH NITRILE LIGANDS AND CRYSTAL-STRUCTURES OF N(C4H9)(4)[PT(PH2SO)CL-3], N(C2H5)(4)[PT(PH2SO)BR-3] AND CIS-PT(PH2SO)(C3H5CN)CL-2

The aqueous reactions of K[Pt(Ph2SO)Cl-3] with nitriles were studied i n different conditions of pH, mainly by Pt-195 and H-1 NMR. At normal pH (approximate to 2.4), the ligands R-CN have produced the neutral co mplexes Pt(Ph2SO)(R-CN)Cl-2. For acetonitrile, only the cis isomer was obtained, while for other nitriles a mixture of the two isomers was f ormed. The Pt-195 NMR spectra of the compounds were measured. The sign als of the cis isomers were observed around -3040 ppm, while those of the trans isomers were found around -3180 ppm. The study has shown tha t the first product formed is the traits isomer, which then isomerizes partially to the cis compounds. The Pt-195 NMR spectra of the product s obtained in neutral medium (pH adjusted to similar to 7 with NaOH) h ave shown several signals depending on the nitrile. Dimeric species of the type Pt(Ph2SO)Cl(mu-NHC(R)O)(2)Pt(Ph2SO)Cl are suggested to exist in solution. Head-to-head and head-to-tail isomers are probably forme d. The crystal structures of N(C4H9)(4)[Pt(Ph2SO)Cl-3] (I), N(C2H5)(4) [Pt(Ph2SO)Br-3] (II) and cis-Pt(Ph2SO)(C3H5CN)Cl-2 (III) were determin ed. The chloro ionic complex is triclinic, P-1, with a = 10.674(2), b = 11.424(2), c = 13.731(2) Angstrom, alpha = 89.54(1), beta = 83.27(1) , gamma = 80.48(1)degrees, Z = 2 and R = 0.042, while the bromo comple x is monoclinic, P2(1)/n, with a = 11.258(3), b = 19.425(4), c = 11.59 0(2) Angstrom, beta = 102.62(2)degrees, Z = 4 and R = 0.053. Crystal I II is orthorhombic, space group P2(1)2(1)2(1), a = 9.532(3), b = 11.78 7(2), c = 15.464(4) Angstrom, Z = 4 and R = 0.031. The compound is the cis isomer. For crystal I, the Pt-Cl bond in trans position to the su lfoxide is 2.312(2) Angstrom. while the cis bonds are 2.282(2) and 2.2 99(2) Angstrom. For the bromo compound (II), the Pt-Br bonds vary betw een 2.397(3) and 2.421(3) Angstrom. In crystal III, the Pt-Cl bond loc ated in trans position to the nitrile is considerably shorter (2.269(3 ) Angstrom) than the Pt-Cl bond in trans position to the sulfoxide lig and (2.311(3) Angstrom). The Pt-S bond distances vary between 2.201(2) and 2.228(3) Angstrom. (C) 1997 Elsevier Science S.A.