Publication details

Octanuclear nickel phosphonate core forming extended and molecular structures



Year of publication 2020
Type Article in Periodical
Magazine / Source CrystEngComm
MU Faculty or unit

Faculty of Science

Keywords octanuclear nickel phosphonates; coordination polymers;
Description Three new nickel phosphonate complexes {[Na2Ni8(L)(6)]center dot nSolv}(m) (L = SAA(3-) (1), BSAA(3-) (2), NAA(3-) (3); Solv = H2O, MeOH; m = 8 (1, 2), 1 (3)) were synthesized. All three complexes possess a novel octanuclear {Ni-8} phosphonate core, which consists of four dinuclear doubly oxygen-bridged units, further interconnected to each other by phosphonate oxygen bridges. The steric features of the ligands influence the aggregation degree. Molecules of 1 and 2 are interconnected by sodium cations into 2D layered and 1D chain extended structures, respectively, while the molecules of 3 with the bulkiest ligand are not bonded with each other. Magnetic properties of the obtained {Ni-8} core unit were studied for complex 1 as a representative of this family of compounds and are reported in detail. Magnetic susceptibility at low temperature is indicative of a singlet ground state. The absence of saturation and the magnetization behavior points to zero-field splitting (ZFS). Simulation of the magnetization data revealed an easy-plane magnetic anisotropy with an axial ZFS parameter D = 7.4 cm(-1). The magnetic properties of 1 were also studied by broken-symmetry DFT calculations (BS-DFT), which revealed the presence of ferromagnetic exchange interactions within the dinuclear units of the {Ni-8} core with a dominant antiferromagnetic interaction between these dinuclear entities. These results are in good agreement with coupling constants derived from the experimental susceptibility and magnetization data.
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