Crystal structure, 195Pt NMR chemical shifts, vibrational spectra, and normal coordinate analyses of trans-dihalogeno-bis(oxalato)platinates(IV), trans-[PtX2(ox)2]2-, X = Cl, Br, I

By reaction of (n-BU4N)(2)[Pt(OX)(2)] With elemental halogens in dichloromethane the complexes trans-[PtX2(ox)(2)](2-) (X = Cl, Br, I) are formed. The crystal structures of trans-(PY2CH2)[PtCl2(ox)(2)].C4H6O3 (1) (monoclinic, space group P2(1)/n, n= 12.119(3), b= 14.926(2), c = 12.666(4) Angstrom, beta = 91.26(3)degrees, Z = 4), trans-(py(2)CH(2)) [PtBr2(ox)(2)] (2) (monoclinic, space group P2(1)/n, a = 7.402(8), b = 16.997(3), c = 14.898(3) Angstrom, beta = 98.15(3)degrees, Z = 4) and trans-(py(2)CH(2))[PtI2(ox)(2)].C3H7NO (3) (orthorhombic, space group Pnma, a = 10.380(9), b = 13.973(2), c = 17.440(4) A, Z = 4) have been determined by single crystal X-ray diffraction analysis. Highly resolution IR and Raman spectra were measured at low temperature (10 K). Using the molecular parameters of the X-ray determinations normal coordinate analyses based on a modified valence force field have been performed and the normal modes of vibration are assigned. The valence force constants are f(d)(PtCl) = 2.19, f(d)(PtBr) = 1.68, f(d)(PtI) = 1.28 mdyn/Angstrom and f(d)(PtO) ranges from 2.71 to 2.82 mdyn/Angstrom. The observed Pt-195 NMR shifts are partial derivative(Pt-195) = 6472.4 (X = Cl), 6027.1 (Br) and 5142.7 ppm (I).