PREPARATION AND SPECTROSCOPIC CHARACTERIZ ATION OF CHLOROTHIOCYANATOPLATINATES(IV) AND CRYSTAL-STRUCTURE OF MER-[(C5H5N)(2)CH2][PTCL3(SCN)(3)]

By treatment of [PtCl6](2-) with SCN- in aqueous solution a mixture of chlorothiocyanatoplatinates(IV) is formed, from which fac-[PtCl3(SCN) (3)](2-) (1), mer-[PtCl(SCN)(3)](2-) (2), cis-[PtCl2(SCN)(4)](2-) (3) and [PtCl(SCN)(5)](2-) (4) have been separated by ion exchange chromat ography on diethylaminoethyl cellulose. The X-Ray structure determinat ion on a single crystal of mer-[(C5H5N)(2)CH2][PtCl3(SCN)(3)] (monocli nic, space group P 2(1)/n, a = 11.1846(10), b = 15.3779(10), c = 11.93 0(2), beta = 94.806(10)degrees, Z = 4) shows, that the thiocyanate gro ups are coordinated via S atoms with Pt-S-C angles of 103.1 degrees up to 108.1 degrees. Using the molecular parameters of X-ray determinati ons the low temperature (10 K) IR and Raman spectra have been assigned by normal coordinate analyses. The valence force constants of the asy mmetrical S'-Pt-Cl-. axes are f(d)(PtS') = 1.86 (1), 1.87 (2), 1.94 (3 ) and 1.93 (4), f(d)(PtCl.) = 1.76 (1), 1.72 (2), 1.78 (3) and 1.89 (4 ), of the S-Pt-S axes are f(d)(PtS) = 1.68 (2), 1.63 (3) and 1.60 (4), of the Cl-Pt-Cl axis is f(d)(PtCl) = 1.95 mdyn/Angstrom (2). The Pt-1 95 NMR spectra from dichlormethane solutions exhibit each one sharp si gnal at 2547.4 (1), 2677.8 (2), 2027.4 (3), and at 2143.1 ppm for tran s-(n-Bu4N)2[PtCl2(SCN)(4)]. The chemical shifts of the complete series [PtCln(SCN)(6-n)](2-), n = 0-6, are calculated in good agreement with observed data using an axes model.