Hydrothermal synthesis and characterization of Pb ₃ Cu ₂ (SeO ₃ ) ₄ Cl ₂ , structurally similar to the mineral sarrabusite

Abstract Hydrothermally synthesized selenite chloride Pb 3 Cu 2 (SeO 3 ) 4 Cl 2 crystallizes in orthorhombic space group Pnma with a = 14.9374(3), b = 19.5578(3), c = 5.23070(10) Å, V = 1,528.11(5) Å 3 , Z = 4, and shows a novel structure type. Its crystal structure contains CuO 4 Cl tetragonal pyramids joint together via Cl apical vertices in pairs. Triangular selenate groups share oxygen atoms with the square planes of copper pyramids, forming chains parallel to the short c axis of the unit cell. The lone pairs of the Se 4+ ions are directed in the opposite side of three oxygen ligands in selenium coordination, contributing to the linkage of neighboring anionic [Cu 2 Cl(SeO 3 ) 4 ] 5− ∞ chains into layers, which alternate with [Pb 3 Cl] 5+ cationic layers in the a axis direction. Topological correlations between the title crystal structure and that of mineral sarrabusite, Pb 5 Cu(SeO 3 ) 4 Cl 4 are discussed. The low-dimensional behavior of Pb 3 Cu 2 (SeO 3 ) 4 Cl 2 is demonstrated by the data from magnetization and heat capacity measurements.