Synthesis, crystal structures, and vibrational spectra of trans-[Pt(N3)4X2]2-,X = Cl, Br, I

By oxidative addition to (n-Bu4N)(2)[Pt(N-3)(4)] with the elemental halogens in dichloromethane trans-(n-Bu4N)(2)-[Pt(N-3)(4)X-2], X = Cl, Br, I are formed. X-ray structure determinations on single crystals of trans-(Ph4P)(2)[Pt(N-3)(4)Cl-2] (triclinic, space group P (1) over bar, a = 10.352(1), b = 10.438(2), c = 11.890(2) Angstrom, alpha = 91.808(12), beta = 100.676(12), gamma = 113.980(10)degrees, Z = 1), trans-(Ph4P)(2)[Pt(N-3)(4)Br-2] (triclinic, space group P (1) over bar, a = 10.336(1), b = 10.536(1), c = 12.119(2) Angstrom, alpha = 91.762(12), beta = 101.135(12), gamma = 112.867(10)degrees, Z = 1) and trans-(Ph4P)(2)[Pt(N-3)(4)I-2] (triclinic, space group P (1) over bar, a = 10.186(2), b = 10.506(2), c = 12.219(2) Angstrom, alpha = 91.847(16), beta = 101.385(14), gamma = 111.965(18)degrees, Z = 1) reveal, that the compounds crystallize isotypically with octahedral centrosymmetric complex anions. The bond lengths are Pt-Cl = 2.324, Pt-Br = 2.472, Pt-I=2.619 and Pt-N = 2.052-2.122 Angstrom. The approximate linear Azidoligands with N-alpha-N-beta-N-gamma-angles = 172.1-176.8 degrees are bonded with Pt-Na-NP-angles = 116.2-121.9 degrees. In the vibrational spectra the platinum halogen stretching vibrations of trans-(n-Bu4N)(2)[Pt(N-3)(4)X-2] are observed in the range of 327-337 (X = Cl), at 202 (Br) and in the range of 145-165 cm(-1) (I), respectively. The platinum azide stretching modes of the three complex salts are in the range of 401-421 cm(-1). Based on 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)(PtCl) = 1.90, f(d)(PtBr) = 1.64, f(d)(PtI) = 1.22, f(d)(PtNalpha) = 2.20-2.27 and f(d)((NNbeta)-N-alpha, (NNgamma)-N-beta) = 12.44 mdyn/ Angstrom.