cis/trans influences on bond distances in square-planar complexes. Crystal structures of trans-dichlorobis(tetrahydrothiophene)palladium(II) and trans-dichlorobis(tetrahydrothiophene)platinum(II)

Crystals of trans-dichlorobis(tetrahydrothiophene)pa and the corresponding platinum(II) compound were prepared by dissolving the metal chloride in tetrahydrothiophene at 363 K and cooling to room temperature. Crystal data at room temperature (MoK alpha(1), lambda = 0.70926 Angstrom) are: [PdCl2(C4H8S)(2)], M(r) = 353.67, monoclinic, C2/c, a = 15.648(3), b = 9.157(1), c = 9.215(2) Angstrom, beta = 111.94(2)degrees, V = 1224.8(2) Angstrom(3), Z = 4, D-x = 1.918 g cm(-3), mu = 2.22 mm(-1), F(000) = 704, R = 0.021 for 872 unique reflections with I greater than or equal to 3 sigma(I); [PtCl2(C4H8S)(2)], M(r) = 442.33, monoclinic, C2/c, a = 15.620(4), b = 9.146(2), c = 9.255(2) Angstrom, beta = 111.98(2)degrees, V = 1226.0(3) Angstrom(3), Z = 4, D-x = 2.396 g cm(-3), mu = 12.29 mm(-1), F(000) = 832, R = 0.056 for 779 reflections with I greater than or equal to 3 sigma(I). Both compounds consist of van der Waals packed mononuclear trans-[MCl(2)(C4H8S)(2)] complexes. The acceptor-donor distances are Pd-Cl 2.296(1); Pd-S 2.323(1); Pt-Cl 2.309(5) and Pt-S 2.305(4) Angstrom. The cis influence of Cl, Cl on a Pd-S or a Pt-S bond length is the same as for I, I. The trans influence of Cl on a Pt-S (thioether) bond is found to be -0.035(16) Angstrom (95% confidence level). It is confirmed that Pt-S(thioether) bonds generally are shorter than corresponding Pd-S bonds.