Synthesis, crystal structure, thermal, photoluminescent and magnetic properties of a new material: Na2[Ni(C2O4)2(H2O)2].6H2O

Abstract A new nickel oxalate complex, sodium diaquabis(oxalato)nickelate(II)hexahydrate {Na 2 [Ni(C 2 O 4 ) 2 (H 2 O) 2 ]·6H 2 O} has been prepared by the method of slow evaporation and characterized by X-ray single crystal diffraction, FT-IR, UV–visible spectroscopy, photoluminescence, TG/DTA analysis and magnetic measurements. The X-ray single crystal analysis shows that the structure of the compound belongs to the triclinic system with P 1 ¯ space group and cell parameters of a  = 6.7853 (5)A, b  = 6.8579 (5)A, c  = 8.8075 (7)A, α  = 87.252(4)°, β  = 67.608(4)°, γ  = 88.718(4)°, Z  = 1. Within the crystal structure, the nickel atom acquires an octahedral environment with six oxygen atoms of which two are from coordinated water molecules and four are from two oxalate ligands. The UV–visible spectrum shows three absorption bands at 236, 376 and 650 nm in the ultraviolet and visible regions, respectively. The compound exhibits ultraviolet (UV) emission at 350 nm when excited at 320 nm at room temperature. The thermogravimetric studies confirm the existence of both hydrated and coordinated water molecules and thermal stability of the compound is 320 °C. Magnetic measurements reveal the occurrence of strong antiferromagnetic interactions between nickel ions in the structure.