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

Abstract

Four novel mixed metal selenites or tellurites containing PdO₄ squares, namely, BaPd(SeO₃)₂, Bi₂Pd(SeO₃)₄, and Pb₂Pd(QO₃)₂Cl₂ (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(SeO₃)₂ contains one-dimensional (1D) [Pd(SeO₃)₂]²⁻ anionic chains composed of PdO₄ units linked by SeO₃²⁻groups in a bidentate bridging fashion. Bi₂Pd(SeO₃)₄ exhibits a complicated 3D architecture constructed by [Bi(SeO₃)]⁺ and [Pd(SeO₃)₂]²⁻ layers that are alternating along the a-axis. The [Pd(SeO₃)₂]²⁻ layers are composed of Pd²⁺ ions bridged by SeO₃²⁻ anions in a bidentate fashion. Pb₂Pd(QO₃)₂Cl₂ (Q = Se, Te) features zero-dimensional (0D) [Pd(QO₃)Cl₂]⁴⁻ (Q = Se, Te) anionic clusters, which are further bridged by Pb²⁺ 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.