Metal phosphonates based on aminomethylenediphosphonate: Syntheses and characterization of Na4Zn{NH3CH(PO3)2}2·4H2O, Ni{NH3CH(PO3H)2}2·xH2O and NaNi2{NH3CH(PO3)(PO3H0.5)}2(H2O)2·2H2O

This paper describes the syntheses of three transition metal diphosphonate compounds: Na4Zn{NH3CH(PO3)2}2·4H2O (1), Ni{NH3CH(PO3H)2}2·xH2O (2) and NaNi2{NH3CH(PO3)(PO3H0.5)}2(H2O)2·2H2O (3). Compound 1 contains chains of image made up of corner-sharing ZnO6 octahedra and CPO3 tetrahedra, which are further connected by tetramers of edge-sharing NaO6 octahedra, forming a three-dimensional open-framework structure. Compound 2 shows a square-grid layer structure where the NiO6 octahedra are corner shared with CPO3 tetrahedra. The adjacent layers are linked by strong inter-layer hydrogen bonds, resulting in a three-dimensional open-network structure with channels where the lattice water molecules reside. The structure of compound 3 is analogous to that of NaCo2{NH3CH(PO3)(PO3H0.5)}2(H2O)2·xH2O in which layers of Ni2{NH3CH(PO3)(PO3H0.5)}2(H2O)2 are connected by NaO6 linkages into an open-framework structure. The magnetic studies show that weak antiferromagnetic interactions are mediated between the nickel ions in compounds 2 and 3. Crystal data for 1: triclinic, space group P-1, image, image, image, image, image, image, image, image. For 2: triclinic, space group P-1, image, image, image, image, image, image, image, image.