Synthesis, Crystal Structures, and Vibrational Spectra of Novel Azidopalladates of the Alkali Metals Cs2[Pd(N3)4] and Rb2[Pd(N3)4]•2/3H2O

The transparent dark orange compounds Cs-2[Pd(N-3)(4)] and Rb-2[Pd(N-3)(4)]center dot 2/3H(2)O 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 P2(1)/c (no. 14) with a = 705.7(2) pm, b = 717.3(2) pm, c = 1125.2(5) pm, beta = 104.58(2)degrees, mP30 for Cs2[Pd(N-3)(4)] and a = 1041.4(1) pm, b 1292.9(2) pm, c = 1198.7(1) pm, beta = 91.93(1)degrees, MP102 for Rb-2[Pd(N-3)(4)]center dot 2/3H(2)O, respectively. Predominant structural features of both compounds are discrete [Pd-II(N-3)(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 C-4h of the spectroscopically relevant unit, [Pd(N-3)(4)](2-) taking into account the site symmetry splitting due to the symmetry reduction in the solid phase.