Synthesis and characterization of a new layered organic-inorganic hybrid nickel(II) 1,4 : 5,8-naphthalenediimide bis-phosphonate, exhibiting canted antiferromagnetism, with T-c similar to 21 K

A new Ni(II) layered hybrid organic-inorganic compound of formula Ni-2[(NDI-BP)(H2O)(2)]center dot 2H(2)O has been prepared in very mild conditions from N,N'-bis(2-phosphonoethyl)napthalene-1,4:5,8-tetracarboximide (NDI-BP ligand) and NiCl2. The X-ray powder structure characterization of the title compound suggests a pillared layered organic-inorganic hybrid structure. The distance between the organic and inorganic layers has been found to be 17.8 angstrom. The inorganic layers consist of corner sharing [NiO5(H2O)] octahedra and they are pillared by the diphosphonate groups. DC and AC magnetic measurements as a function of temperature and field indicate the presence of 2D antiferromagnetic exchange interactions between the nearest-neighbor Ni(II) ions below 100 K. A long-range magnetic ordering at T-c similar to 21 K has been established and is attributed to the presence of spin canting. AC magnetic measurements as a function of temperature at different frequencies confirm the occurrence of the magnetic ordering temperature at T = 21 K and the presence of a slight structural disorder in the title compound.