Novel Co and Ni Metal Complexes and Ferromagnets by the Combination of 2-Pyridyl Oximes with Polycarboxylic Ligands.

The use of 2-pyridyl oximes in metal complexes chemistry has been extensively investigated in the last few decades as a fruitful source of species with interesting magnetic properties. In this work, the initial combination of pyridine-2-amidoxime (pyaoxH) and 2-methyl pyridyl ketoxime (mpkoH) with isonicotinic acid (HINA) and 3,5-pyrazole dicarboxylic acid (Hpdc) has provided access to three new compounds, [Ni(INA)(pyaox)(pyaoxH)(DMF)] (), Co(mpko)(mpkoH)(OMe)(HO) (), and [Co(OH)(Hpdc)(Hpdc)] (). displays a square-planar metal topology, being the first example that bears simultaneously HINA and pyaoxH in their neutral or ionic form. The neighbouring Ni units in are held together through strong intermolecular hydrogen bonding interactions, forming a three-dimensional supramolecular framework. and are mixed-valent CoCo and CoCo compounds with a bowtie and trigonal bipyramidal metal topology, accordingly. Direct current and alternate current magnetic susceptibility studies revealed that the exchange interactions between the Ni ions in are ferromagnetic ( = 1.79(4) cm), while exhibits weak AC signals in the presence of a magnetic field. The syntheses, crystal structures, and magnetic properties of are discussed in detail.