Cu5Sb2O8SiO4, an open framework structure with copper uncommon coordination modes: Cu[2+2+2]O6 and Cu[4+4]O8

Cu5Sb2O8SiO4 is orthorhombic, space group Pcca, with a = 19.031 (2), b = 9.3944 (6), c = 9.602 (2) Å, and z = 8. Its crystal structure was determined using single crystal X-ray diffraction (R1 = 0.0432 and wR2 = 0.1146). The compound presents a parwelite-like structure. Its anionic three-dimensional framework is built up of corner-sharing SbO6 octahedra and SiO4 tetrahedra, delimiting interconnected channels wherein Cu2+ with different coordination modes, are located. The χM and χMT product versus T plots, showed the Cu5Sb2O8SiO4 material to exhibit an anti-ferromagnetic character with a Neel temperature of about 27 K.