Insights into the Synthesis Parameters Effects on the Structural, Morphological, and Magnetic Properties of Copper Oxide Nanoparticles.

The present study aims at the integration of the "oxalic conversion" route into "green chemistry" for the synthesis of copper oxide nanoparticles (CuO-NPs) with controllable structural, morphological, and magnetic properties. Two oxalate-containing precursors (HCO.2HO and (NH)CO.

Crystal structure of bis-[4-(di-methyl-amino)-pyridinium] aqua-bis-(oxalato)oxidovanadate(IV) dihydrate.

The title organic-inorganic hybrid salt, (C7H11N2)2[V(C2O4)2O(H2O)]·2H2O, shows a distorted octa-hedral coordination environment for the vanadium(IV) atom in the anion (point group symmetry 2), with four O atoms from two symmetry-related chelating oxalate dianions and two O atoms in trans configuration from a coordinating water mol-ecule and a terminal vanadyl O atom. In the crystal, (001) layers of cations and anions alternate along [001]. The anionic layers are built up by inter-molecular O-H⋯O hydrogen bonds involving the coordinating and solvent water mol-ecules.

Crystal structure and spectroscopic analysis of a new oxalate-bridged Mn(II) compound: catena-poly[guanidinium [[aqua-chlorido-manganese(II)]-μ2-oxalato-κ(4) O (1),O (2):O (1'),O (2')] monohydrate].

As part of our studies on the synthesis and the characterization of oxalate-bridged compounds M-ox-M (ox = oxalate dianion and M = transition metal ion), we report the crystal structure of a new oxalate-bridged Mn(II) phase, {(CH6N3)[Mn(C2O4)Cl(H2O)]·H2O} n . In the compound, a succession of Mn(II) ions (situated on inversion centers) adopting a distorted octa-hedral coordination and bridged by oxalate ligands forms parallel zigzag chains running along the c axis. These chains are inter-connected through O-H⋯O hydrogen-bonding inter-actions to form anionic layers parallel to (010).

Imidazolium trans-di-aqua-dioxalato-chromate(III) dihydrate.

In the title hydrated mol-ecular salt, (C3H5N2)[Cr(C2O4)2(H2O)2]·2H2O, the complete cation is generated by a crystallographic twofold rotation axis, with one C atom lying on the rotation axis. The complete anion is generated by crystallographic inversion symmetry (Cr(III) site symmetry -1), to generate a slightly distorted CrO6 octa-hedron with trans water mol-ecules and chelating oxalate dianions. The oxalate ion is almost planar (r.

3-Amino-pyridinium trans-diaqua-dioxalato-chromate(III).

In the structure of the title compound, (C₅H₇N₂)[Cr(C₂O₄)₂(H₂O)₂], two crystallographically independent formula units are present. Both chromium atoms are six-coordinated in a distorted octa-hedral geometry by two chelating equatorial oxalato ligands and two axial water mol-ecules. The [Cr(C₂O₄)₂(H₂O)₂]⁻ anions and C₅H₇N₂ ⁺ cations are linked through a complex three-dimensional hydrogen-bonding network consisting of N-H⋯O and O-H⋯O inter-actions.

2-Amino-5-chloro-pyridinium cis-diaqua-dioxalatochromate(III) sesquihydrate.

In the crystal structure of the title compound, (C(5)H(6)ClN(2))[Cr(C(2)O(4))(2)(H(2)O)(2)]·1.5H(2)O, the Cr(III) atom adopts a distorted octa-hedral geometry being coordinated by two O atoms of two cis water mol-ecules and four O atoms from two chelating oxalate dianions. The cis-diaqua-dioxalatochromate(III) anions, 2-amino-5-chloro-pyridinium cations and uncoordinated water mol-ecules are linked into a three-dimensional supra-molecular array by O-H⋯O and N-H⋯O hydrogen-bonding inter-actions.

4-Amino-pyridinium trans-diaqua-dioxalatochromate(III) monohydrate.

In the non-centrosymmetric structure of the title compound, (C(5)H(7)N(2))[Cr(C(2)O(4))(2)(H(2)O)(2)]·H(2)O, the Cr(III) ion has a slightly distorted octa-hedral coordination environment defined by two chelating oxalato ligands in equatorial positions and two water mol-ecules in axial positions. An extensive three-dimensional network of hydrogen bonds involving all the water mol-ecules, the 4-amino-pyridinium cation and some of the oxalate O atoms contributes to the stabilization of the structure. π-π inter-actions between adjacent pyridine rings provide additional stability of the crystal packing, with a closest distance between pyridine mean planes of 3.