Synthesis, crystal structure, vibrational spectra, and normal coordinate analysis of trans-(n-Bu4N)4[Pt(ECN)2(ox)2], E = S, Se

By reaction of (n-Bu4N)(2)[Pt(ox)(2)] with (SCN)(2) and (SeCN)(2) in dichloromethane trans-(n-Bu4N)(2)[Pt(SCN)(2)(ox)(2)] (1) und trans-(n-Bu4N)(2)[Pt(SeCN)(2)(ox)(2)] (2) are formed. The crystal structures of 1 (triclinic, space group P (1) over bar, a=10.219(2), b=11.329(2), c=12.010(3) Angstrom, alpha =114.108(15), beta =104.797(20), gamma = 102.232(20)degrees, Z=1) and 2 (triclinic, space group P (1) over bar, a = 10.288(1), b = 11.332(1), c=12.048(1) Angstrom, alpha =114.391(9), beta =103.071(10), gamma =102.466(12)degrees, Z=1) reveal, that the compounds crystallize isotypically with centrosymmetric complex anions. The bond lengths are Pt-S = 2.357, Pt-Se = 2.480 and Pt-O = 2.011 (1) und 2.006 Angstrom (2). The oxalato ligands are nearly plane with O-C-C-O torsion angles of 1.7-3.6 degrees. The via S or Se coordinated linear groups are inclined between both oxalato ligands with Pt-E-C angles of 100.4 (E = S) and 97.4 degrees (Se). In the vibrational spectra the PtE stretching vibrations are observed at 299-314 (1) and 189-200 cm(-1) (2). The PtO stretching vibrations are coupled with internal vibrations of the oxalato ligands and appear in the range of 400-800 cm(-1). Based on the molecular parameters of the X-ray determinations the IP and Raman spectra are assigned by normal coordinate analysis. The valence force constants are f(d)(PtS)=1.75, f(d)(PtSe) = 1.35 and f(d)(PtO)=2.77mdyn/Angstrom. The NMR shifts are delta(Pt-195) = 5435.2 (1), 5373.7 (2) and delta(Se-77) = 353.2 ppm with the coupling constant (1)J(SePt) = 37.4 Hz.