PLATINUM(II) COMPLEXES OF THE TRIDENTATE THIOETHER LIGANDS RS(CH2)(3)S(CH2)(3)SR (R=ET, IPR, PH) - STRUCTURES OF [PTCL(IPRS(CH2)(3)S(CH2)(3)SIPR)][BF4], [PTI(PHS(CH2)(3)S(CH2)(2)SPH)][BF4], AND RS(CH2)(3)S(CH2)(3)SIPR)][BF4](2)CENTER-DOT-CH2CL2

The tridentate thioether ligands RS(CH2)(3)S(CH2)(3)SR (L(1), R = Et; L(2), R = iPr, L(3), R = Ph) were synthesized by nucleophilic addition of thiolate, SR(-), to the ditosylate TsO(CH2)(3)S(CH2)(3)OTs. The co mplexes [PtX(L(n))][BF4] were prepared by displacement of 1,5-COD from [PtX(x)(1,5-COD)](X = Cl, I) in the presence of one equivalent of AgB F4 and one equivalent of thioether ligand. [PtCl(L(2))][BF4] crystalli zed in the monoclinic space group P2(1)/c with a = 10.409(6), b = 14.1 80(4), c = 13.726(8) Angstrom, beta = 104.49(4)degrees, V = 1961(2) An gstrom 3, and Z = 4. The structure refined to R = 5.62% and R(w) = 6.8 6% for 2121 reflections with F-0(2) > 3 sigma(F-0(2)). [PtI(L(3))][BF4 ] crystallized in the monoclinic space group P2(1)/n with a = 13.415(4 ), b = 12.350(5), c = 14.316(5) Angstrom, beta = 107.48(3)degrees, V = 2262(1) Angstrom(3), and Z = 4. The structure refined to R = 4.85% an d R(w) = 6.33% for 2168 reflections with F-0(2) > 3 sigma(F-0(2)). In both compounds, the thioether ligand acts as a tridentate chelator occ upying three of the four sites of the square-planar Pt(II) complex. Va riable temperature C-13{H-1} NMR verified that there are three possibl e stereoisomers for these complexes resulting from inversion at sulphu r: meso-A, meso-B, and racemic. Thermodynamic parameters were calculat ed for the interconversion among isomers of [PtCl(L(2))][BF4] by a ful l line-shape analysis. Removal of chloride ligand from [PtCl(L(2))][BF 4] with Ag+ in the presence of PPh(3) yielded the phosphine adduct [Pt (PPh(3))(L(2))][BF4](2), which crystallized in the triclinic space gro up P (1) over bar with a = 13.266(3), b = 11.315(2), c = 13.970(2) Ang strom, alpha = 106.04(2)degrees, beta = 84.95(2)degrees, gamma = 86.56 (2)degrees, V = 1999.7(7) Angstrom(3), and Z = 2. The structure refine d to R = 4.22% and R(w) = 5.38% for 4493 reflections with F-0(2) > 3 s igma(F-0(2)). Unlike the two halide complex structures, which crystall ized in the meso-B form, [Pt(PPh(3))(L(2))][BF4](2) crystallized in th e racemic form.