SYNTHESIS AND CHARACTERIZATION OF AND STEREOSELECTIVE OXIDATIVE ADDITION OF CHLORINE OR BROMINE TO [NBU4][PT(C6F5)2(C5H4NS)]

The title complex [NBu4][Pt(C6F5)2(C5H4NS)] (1; C5H4NS = pyridine-2-th iolate) can be obtained in high yield hy reaction (1:2) of [NBu4]2[Pt( mu-Cl)(C6F5)2]2 with in situ generated LiC5H4NS. 1 is suggested to be monomeric. The N end of the chelate pyridine-2-thiolate ligand in 1 ca n be released by reaction with P(C6H5)3, which gives [NBu4][Pt(C6F5)2( C5H4NS){P(C6H5)3}] (2). 1 reacts with CCl4 solutions Of Cl2 or Br2, yi elding [NBu4][Pt(C6F5)2(C5H4NS)X2] (X = Cl (3a), Br (3b)). In each rea ction a single product can be spectroscopically detected, which means that the oxidative addition proceeds stereoselectively. In order to es tablish the actual geometry of the reaction product, the molecular str ucture of 3b was determined by X-ray diffraction. 3b crystals are mono clinic, space group C2/c, with a = 2186.0(13) pm, b = 2088.6(4) pm, c = 1703.5-(5) pm, beta = 99.43(1)-degrees, V = 7672 x 10(6) pm3, and Z = 8. The structure determination revealed that the anion exists as the enantiomeric couple OC-6-42-A and OC-6-42-C. Substitution of one of t he halogens attached to Pt by a neutral or anionic ligand can be easil y accomplished, and accordingly, the complexes [Pt(C6F5)2(C5H4NS)(CN-t -C4H9)X] (X = Cl (4a), Br (4b)) and [NBu4][Pt(C6F5)2(C5H4NS)BrCl] (3c) have been prepared. A single product is obtained in each case, sugges ting that the substitution reaction proceeds with stereoretention. The molecular structure of 4b was also determined by X-ray methods. 4b cr ystals are triclinic, space group P1BAR, with a = 913.1(2) pm, b = 108 5.1(2) pm, c = 1363.9(3) pm, alpha = 89.50(1)-degrees, beta = 72.82(2) -degrees, gamma = 77.81(2)-degrees, V = 1260 x 10(6) pm3, and Z = 2. T he molecule exists as the enantiomeric couple OC-6-54-A and OC-6-54-C, showing that the equatorial halogenide in its parent compound 3b is m ore labile than the axial one.