Crystal structure and magnetic properties of NaCuII[(CuII3O)(PO4)2Cl]

A new copper(II) oxide phosphate chloride, NaCuII[(CuII3O)(PO4)2Cl], has been synthesized by flux synthesis. Single-crystal X-ray diffraction data show that the title compound crystallizes in the monoclinic system, space group P21/c (No. 14), with lattice parameters a=8.392(2) Å, b=6.3960(10) Å, c=16.670(2) Å, β=109.470(10)°, V=843.6(3) Å3, Z=4. The crystal structure is characterized by a complex chain of copper-centered polyhedra running along [0 1 0] which are connected by phosphate tetrahedra. The resulting three-dimensional polyhedra framework exhibits channels filled by additional copper and sodium atoms. Field and temperature dependent measurements of the specific heat and the magnetic susceptibility reveal low-dimensional magnetic behavior. The compound starts to decompose at 700 K under release of oxygen and evaporation of CuICl as shown by simultaneous thermogravimetry and mass spectrometry.