Two nickel(II) carboxyphosphonates with different supramolecular structures: synthesis, crystal structures and magnetic properties

Two Ni(II) carboxyphosphonates, namely [Ni(H4L)2] (1) and [Ni(H3L)(H2O)]·2H2O (2) (H5L=HOOCC6H4CH2N(CH2PO3H2)2), have been hydrothermally synthesized. Structural analyses reveal that 1 shows a two-dimensional (2D) inorganic layer structure, and the layers are further packed into a three-dimensional (3D) supramolecular structure through the interlayer hydrogen-bonding interactions. In 2, two adjacent {NiO5N} polyhedra are connected to form a {Ni2O8N2} dimer, and these dimers are further linked by {CPO3} tetrahedra to form a one-dimensional (1D) chain. Consecutive chains are further connected by the intermolecular hydrogen-bonding interactions, resulting in a 2D supramolecular layer structure. Magnetic analyses exhibited that 1 shows major antiferromagnetic behavior, whereas 2 displays ferromagnetic interactions at low temperatures. Meanwhile, the magnetic properties of 1 and 2 have also been quantified using the Curie–Weiss law and the PHI program package, respectively. Two nickel(II) carboxyphosphonates with different structures showed different magnetic behaviors. Meanwhile, the magnetic properties of 1 and 2 have also been quantified using the Curie–Weiss law and the PHI program package.