Abstract
The title compound, {[K4Ni2(C7H6N4O7)2]·4.8H2O} n , was obtained as a result of a template reaction between oxalohydrazide-hydroxamic acid, formaldehyde and nickel(II) nitrate followed by partial hydrolysis of the formed inter-mediate. The two independent [Ni(C7H6N4O7)]2- complex anions exhibit pseudo-C S symmetry and consist of an almost planar metal-containing fragment and a 1,3,5-oxadiazinane ring with a chair conformation disposed nearly perpendicularly with respect to the former. The central NiII atom has a square-planar N2O2 coordination arrangement formed by two amide N and two carboxyl-ate O atoms. In the crystal, the nickel(II) complex anions form layers parallel to the ab plane. Neighboring complex anion layers are connected by layers of potassium cations for which two of the four independent cations are disordered over two sites [ratios of 0.54 (3):0.46 (3) and 0.9643 (15):0.0357 (15)]. The framework is stabilized by an extensive system of hydrogen bonds where the water mol-ecules act as donors and the carb-oxy-lic O atoms, the amide O atoms and the oxadiazinane N atoms act as acceptors.
Highlights
Chemical contextCoordination compounds of paramagnetic metal ions based on polydentate ligands comprising amide, hydrazide and hydroxamate functional groups are of great interest as they often form novel oligonuclear structures with interesting supramolecular features (Mezei et al, 2007; Strotmeyer et al, 2003)
The title compound, {[K4Ni2(C7H6N4O7)2]Á4.8H2O}n, was obtained as a result of a template reaction between oxalohydrazidehydroxamic acid, formaldehyde and nickel(II) nitrate followed by partial hydrolysis of the formed intermediate
Neighboring complex anion layers are connected by layers of potassium cations for which two of the four independent cations are disordered over two sites [ratios of 0.54 (3):0.46 (3) and 0.9643 (15):0.0357 (15)]
Summary
Coordination compounds of paramagnetic metal ions based on polydentate ligands comprising amide, hydrazide and hydroxamate functional groups are of great interest as they often form novel oligonuclear structures with interesting supramolecular features (Mezei et al, 2007; Strotmeyer et al, 2003). These compounds exhibit unusual magnetic properties (Pavlishchuk et al, 2010; Gumienna-Kontecka et al, 2007; Pavlishchuk et al, 2011; Huang et al, 2014) and have potential biological activity (Raja et al, 2012). The plausible mechanism of formation for (1) includes the deprotonation of oxalohydrazidehydroxamic acid and coordination to the metal ions in a tetradentate mode, followed by template condensation of two hydrazide moieties with three molecules of formaldehyde and metal-promoted hydrolysis of the hydroxamate group of the formed intermediate, which
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