Preparation, crystal structure and magnetic properties of Ni2(dpa)2(pyz)(H2O)4

A Ni(II)-based dimer structure, Ni2(dpa)2(pyz)(H2O)4 (dpa = 2,6-pyridine dicarboxylic acid dianion, pyz: pyrazine), has been prepared using hydrothermal synthesis and the solid-state magnetic properties have been evaluated. In the dimeric structure, the planar tridentate 2,6-pyridine dicarboxylic acid dianion coordinates to a Ni(II) ion in a meridional fashion and defines the equatorial plane of the complex. The fourth equatorial coordination site is then occupied by a pyrazine molecule that functions as a linear bidentate ligand bridging two Ni(II) complexes to form a dimer. The axial positions of each Ni(II) complex are occupied by two water molecules to form a distorted octahedral geometry. Susceptibility and magnetization measurements show that both intra-dimer and inter-dimer exchange interactions are weakly antiferromagnetic. The fitting of the magnetic data also indicates the existence of a large axial zero-field splitting term that contributes to the small magnetization even under high fields.

Graphical abstractA Ni(II)-based dimeric structure has been prepared and characterized. Dimers are linked through an extensive hydrogen bonding network. Magnetic susceptibility and magnetization have been measured and analyzed for this compound.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► T-shaped building blocks may be used to synthesize ladder-like structures ► Weak antiferromagnetic coupling is mediated via hydrogen bonding and pyrazine. ► Strong zero-field splitting results in low magnetization under high field.