Abstract.Three (3) (opicHA = 2-picolinehydroxamic acid) were synthesized in order to retrace structural trends caused by the change of the ionic radius of the central metal ion as well as to assess the effect of the axial ligands on the arrangement of metallacrowns. The complexes were characterized by elemental analysis, ESI-mass spectrometry, IR spectroscopy, and
The title compound, [Cu2(C5H7N2)(C4H10NO2)Cl2(C5H8N2)], is a pyrazolate aminoalcohol complex which contains two dimethylpyrazole molecules in monodentate and bidentate-bridged coordination modes and a monodeprotonated diethanolamine molecule. Both copper atoms are involved in the formation of non-planar five-membered chelate rings. One Cu atom is in a distorted tetrahedral environment formed by the pyridine nitrogen atom of the protonated dimethylpyrazole molecule, the N atom of the deprotonated bridged dimethylpyrazole, the Cl atom and the bridged O atom of the monodeprotonated diethanolamine. The second Cu atom has an intermediate environment between trigonal bipyramidal and square pyramidal, formed by the N atom of the deprotonated bridged dimethylpyrazole, the Cl atom and the N atom of the aminoalcohol, and two O atoms of the deprotonated and protonated OH groups. In the crystal, N—H...Cl hydrogen bonds link the molecules into antisymmetric chains running along the a-axis direction. Adjacent chains are connected by O—H...O hydrogen bonds involving the hydroxyl group as donor.
In C6H6N2O2·H2O, the N-hydroxypicolinamide molecule adopts a strongly flattened conformation. O—H⋯O interactions and π–π stacking interactions between the pyridine rings organize the crystal components into columns extending along the b axis while N—H⋯N hydrogen bonds link these columns into a two-dimensional framework parallel to (100).
The ZnII ion lies on a crystallographic twofold axis and has distorted tetrahedral coordination geometry. Two weak C—H⋯S intramolecular hydrogen bonds exist between the bipyridyl and thiol groups. In the crystal, molecules are linked by weak C—H⋯O and C—H⋯S hydrogen bonds, forming a three-dimensional supramolecular architecture.
In the unit cell of the title compound, C5H7N3O, there are two conformers (A and B) which differ in the position of the oxime group with respect to the protonated pyrazole nitrogen (trans in the A conformer and cis in the B conformer) and in the geometric parameters. The oxime group exists in the nitroso form in both conformers. In the crystal, molecules are linked by intermolecular N—H⋯O and N—H⋯N hydrogen bonds into zigzag-like chains along the b axis.
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