Synthesis, crystal structures, and vibrational spectra of novel azidopalladates of the alkali metals Cs2[Pd(N3)4] and Rb2[Pd(N3)4]·2/3H2O

Abstract

The transparent dark orange compounds Cs2[Pd(N3)4] and Rb2[Pd(N3)4]·2/3H2O are synthesized by reaction of the respective binary alkali metal azides with K2PdCl4 in aqueous solutions. According to single-crystal X-ray diffraction investigations, the novel ternary azidopalladates(II) crystallize in the monoclinic space group P21/c (no. 14) with a = 705.7(2) pm, b = 717.3(2) pm, c = 1125.2(5) pm, β = 104.58(2)°, mP30 for Cs2[Pd(N3)4] and a = 1041.4(1) pm, b = 1292.9(2) pm, c = 1198.7(1) pm, β = 91.93(1)°, mP102 for Rb2[Pd(N3)4]·2/3H2O, respectively. Predominant structural features of both compounds are discrete [PdII(N3)4]2– anions with palladium in a planar coordination by nitrogen, but differing in point group symmetries., The vibrational spectra of the compounds are analyzed based on the idealized point group C4h of the spectroscopically relevant unit, [Pd(N3)4]2– taking into account the site symmetry splitting due to the symmetry reduction in the solid phase.