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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 2 ) and 2-methyl pyridyl ketoxime (mpkoH) with isonicotinic acid (HINA) and 3,5-pyrazole dicarboxylic acid (H 3 pdc) has provided access to three new compounds, [Ni 4 (INA) 2 (pyaox) 2 (pyaoxH) 2 (DMF) 2 ] ( 1 ), [Co 5 (mpko) 6 (mpkoH) 2 (OMe) 2 (H 2 O)](ClO 4 ) 6 ( 2 ), and [Co 5 (OH)(Hpdc) 5 (H 2 pdc)] ( 3 ). 1 displays a square-planar metal topology, being the first example that bears simultaneously HINA and pyaoxH 2 in their neutral or ionic form. The neighbouring Ni 4 units in 1 are held together through strong intermolecular hydrogen bonding interactions, forming a three-dimensional supramolecular framework. 2 and 3 are mixed-valent Co 4 III Co II and Co 2 III Co II 3 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 II ions in 1 are ferromagnetic ( J = 1.79(4) cm -1 ), while 2 exhibits weak AC signals in the presence of a magnetic field. The syntheses, crystal structures, and magnetic properties of 1-3 are discussed in detail.

The goal of this work is to model the nature of the chemical species [CdCl 2 (extractant) 2 ] that are formed during the solvent (or liquid-liquid) extraction of the toxic cadmium(II) from chloride-containing aqueous media using hydrophobic 2-pyridyl ketoximes as extractants. Our coordination chemistry approach involves the study of the reactions between cadmium(II) chloride dihydrate and phenyl 2-pyridyl ketoxime (phpaoH) in water-containing acetone. The reactions have provided access to complexes [CdCl 2 (phpaoH) 2 ]∙H 2 O ( 1 ∙H 2 O) and {[CdCl 2 (phpaoH)]} n ( 2 ); the solid-state structures of which have been determined by single-crystal X-ray crystallography. In both complexes, phpaoH behaves as an N , N '-bidentate chelating ligand. The complexes have been characterized by solid-state IR and Raman spectra, and by solution 1 H NMR spectra. The preparation and characterization of 1 ∙H 2 O provide strong evidence for the existence of the species [CdCl 2 (extractant) 2 ] that have been proposed to be formed during the liquid-liquid extraction process of Cd(II), allowing the efficient transfer of the toxic metal ion from the aqueous phase into the organic phase., Competing Interests: The authors declare no conflict of interest.

The reactions of methyl(2-pyridyl)ketone oxime, (py)C(Me)NOH, with manganese(II) sulfate monohydrate have been investigated. The reaction between equimolar quantities of MnSO(4) . H(2)O and (py)C(Me)NOH in H(2)O lead to the dinuclear complex [Mn(2)(SO(4))(2){(py)C(Me)NOH}(4)] . (py)C(Me)NOH, 1 . (py)C(Me)NOH, while employment of NaOMe as base affords the compound [Mn(HCO(2))(2){(py)C(Me)NOH}(2)] (2). The structures of both compounds have been determined by single crystal X-ray diffraction. In both complexes, the organic ligand chelates through its nitrogen atoms. The IR data are discussed in terms of the nature of bonding and the structures of the two complexes.