Synthesis, crystal structures, and vibrational spectra of trans-[Pt(N3)4(ECN)2]2-, E = S, Se

By oxidative addition to (n-Bu4N)(2)[Pt(N-3)(4)] with dirhodane in dichloromethane trans-(n-Bu4N)(2)- [Pt(N-3)(4)(SCN)(2)] and by ligand exchange of trans-(n-Bu4N)(2)[Pt(N-3)(4)I-2] with Pb(SeCN)(2) trans-(n-Bu4N)(2)- [Pt(N-3)(4)(SeCN)(2)] are formed. X-ray structure determinations on single crystals of trans-(Ph4P)(2)[Pt(N-3)(4)(SCN)(2)] (triclinic, space group P (1) over bar, a = 10.309(3) b = 11.228(2), c = 11.967(2) Angstrom, alpha = 87.267(13), beta = 75.809(16), gamma = 65.312(17)degrees, Z=1) and trans-(Ph4P)(2)[Pt(N-3)(4)(SeCN)(2)] (triclinic, space group P (1) over bar, a = 9.1620(10), b = 10.8520(10), c = 12.455(2) Angstrom, alpha = 90.817(10), beta = 102.172(10), gamma = 92.994(9)degrees, Z = 1) reveal, that the compounds crystallize isotypically with octahedral centrosymmetric complex anions. The bond lengths are Pt-S = 2.337, Pt-Se = 2.490 and Pt-N = 2.083 (S), 2.053 Angstrom (Se). The approximate linear Azidoligands with N-alpha-N-beta-N-gamma-angles = 172,1-175,0 degrees are bonded with Pt-N-alpha-N-beta-angles = 116,7-120,5 degrees. In the vibrational spectra the platinum chalcogen stretching vibrations of trans-(n-Bu4N)(2)[Pt(N-3)(4)(ECN)(2)] are observed at 296 (E = S) and in the range of 186-203 cm(-1) (Se). The platinum azide stretching modes of the complex salts are in the range of 402-425 cm(-1). Based an the molecular parameters of the X-ray determinations the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants are f(d)(PtS) = 1.64, f(d)(PtSe) = 1.36, f(d)(PtNalpha) = 2.33 (S), 2.40 (Se) and f(d)((NNbeta)-N-alpha, (NNgamma)-N-beta) = 12.43 (S), 12.40 mdyn/A (Se).