cis/trans influences on square-planar platinum(II) complexes. Structure of cis-bis(dimethyl sulfoxide)dinitratoplatinum(II)

cis-[Pt{(CH3)2SO}2(NO3)2], M(r) = 475.36, monoclinic, P2(1)/c, a = 9.006 (1), b = 14.209 (2), c = 10.908 (2) angstrom, beta = 117.88 (1)-degrees, V = 1233.9 (2) angstrom 3, Z = 4, D(x) = 2.559 Mg m-3, lambda(Mo K-alpha)BAR = 0.7107 angstrom, mu = 11.84 mm-1, F(000) = 896, T = 293 K, R = 0.033 for 1763 unique reflections [I > 3-sigma(I)]. The Pt atom coordinates two S atoms from two dimethyl sulfoxide ligands and two O atoms from different nitrate ions in a slightly distorted square-planar geometry (maximal deviation 0.10 angstrom) in a cis arrangement. The compound consists of van der Waals packed molecules appearing in pairs with a Pt-Pt distance of 4.008 (1) angstrom. The acceptor-donor distances observed are: Pt-S = 2.214 (3), 2.220 (3) and Pt-O = 2.040 (9), 2.059 (9) angstrom. These are almost the same as the corresponding ones previously found in tetrakis(dimethyl sulfoxide)platinum(II) bis(trifluoromethanesulfonate) where two dimethyl sulfoxide ligands bond to Pt via their O atoms, also in a cis position. A literature survey of platinum dimethyl sulfoxide compounds shows that the Pt-S distance is significantly affected by both cis and trans influences.