New mixed metal selenites and tellurites containing Pd2+ ions in a square planar geometry.

Four novel mixed metal selenites or tellurites containing PdO(4) squares, namely, BaPd(SeO(3))(2), Bi(2)Pd(SeO(3))(4), and Pb(2)Pd(QO(3))(2)Cl(2) (Q = Se, Te), have been prepared and structurally characterized by single crystal X-ray diffraction analyses. These compounds exhibit three different types of anionic structures. BaPd(SeO(3))(2) contains one-dimensional (1D) [Pd(SeO(3))(2)](2-) anionic chains composed of PdO(4) units linked by SeO(3)(2-) groups in a bidentate bridging fashion. Bi(2)Pd(SeO(3))(4) exhibits a complicated 3D architecture constructed by [Bi(SeO(3))](+) and [Pd(SeO(3))(2)](2-) layers that are alternating along the a-axis. The [Pd(SeO(3))(2)](2-) layers are composed of Pd(2+) ions bridged by SeO(3)(2-) anions in a bidentate fashion. Pb(2)Pd(QO(3))(2)Cl(2) (Q = Se, Te) features zero-dimensional (0D) [Pd(QO(3))Cl(2)](4-) (Q = Se, Te) anionic clusters, which are further bridged by Pb(2+) cations into a 3D network. The results of optical diffuse-reflectance spectrum measurements and band structure calculations based on DFT methods indicate that all the compounds are wide-band-gap semiconductors.