Structure and vibrational spectra of cis-diaquatetra-chloroplatinum(IV)-(18-crown-6)-water (1/1/2), cis-[PtCl4(H2O)2]·(18-cr-6)·2H2O

Abstract

The title compound, cis-[PtCl4(H2O)2]·(18-cr-6)·2H2O(3), crystallizes from water in the orthorhombic space group Pbcn with lattice constants a= 7.9842(12) Å, b=16.550(3) Å, c= 18.027(4) Å, Z= 4. The crystal structure was solved by direct methods. The refinement converged to final wR2= 0.0485 for 2307 data (R1= 0.0187 for 1672 observed reflections). The platinum complex cis-[PtCl4(H2O)2] exhibits crystallographically imposed C2 symmetry with small deviations from C2v symmetry, only. Each of the two aqua ligands forms an O-H...O hydrogen bond to a water molecule in such a way that H4O2 units are yielded. Their three terminal hydrogen atoms form O-H...O hydrogen bonds to three oxygen atoms of the crown ether molecule. Thus, the crystal is threaded by chains built up of 18-crown-6/cis-[PtCl4(H2O)2]·2H2O units. The crown ether exhibits crystallographically imposed Ci symmetry and D3d symmetry in rough approximation. The Raman and IR spectra of 3 are as expected for a complex [PtCl4(H2O)2] with aqua ligands in mutual cis position.