Aqua­bis(3,5-dimethyl-1H-pyrazole-κN)(oxalato-κ2 O,O′)copper(II)

In the title compound, [Cu(C2O4)(C5H8N2)2(H2O)], the CuII atom is coordinated in a slightly distorted square-pyramidal geometry by two N atoms belonging to the two 3,5-dimethyl-1H-pyrazole ligands, two O atoms of the oxalate anion providing an O,O′-chelating coordination mode, and an O atom of the water mol­ecule occupying the apical position. The crystal packing shows a well defined layer structure. Intra-layer connections are realised through a system of hydrogen bonds while the nature of the inter-layer inter­actions is completely hydro­phobic, including no hydrogen-bonding inter­actions

La théorie variation des rayons complexes pour le calcul des vibrations moyennes fréquences

A new approach named the "Variational Theory of Complex Rays" is introduced for computing the vibrations of elastic structures weakly damped in the medium frequency range. Emphasis has been placed here on the most fundamental aspects. The effective quantities (elastic energy, vibration intensity ...) are evaluated after computing a small system of equations which does not derive from a finite element dicretization of the structure. Numerical examples related to plates show the interest and the possibilities ofthe VTRC

Crystal structure of poly[diaqua(μ-2-carboxyacetato-κ3O,O′:O′′)(2-carboxyacetato-κO)di-μ-chlorido-dicobalt(II)]

The asymmetric unit of the title polymer, [Co2(C3H3O4)2Cl2(H2O)2]n, comprises one CoII atom, one water molecule, one singly deprotonated malonic acid molecule (HMal−; systematic name 2-carboxyacetate) and one Cl− anion. The CoII atom is octahedrally coordinated by the O atom of a water molecule, by one terminally bound carboxylate O atom of an HMal− anion and by two O atoms of a chelating HMal− anion, as well as by two Cl− anions. The Cl− anions bridge two CoII atoms, forming a centrosymmetric Co2Cl2 core. Each malonate ligand is involved in the formation of six-membered chelate rings involving one CoII atom of the dinuclear unit and at the same time is coordinating to another CoII atom of a neighbouring dinuclear unit in a bridging mode. The combination of chelating and bridging coordination modes leads to the formation of a two-dimensional coordination polymer extending parallel to (001). Within a layer, O—Hwater...Cl and O—Hwater...O hydrogen bonds are present. Adjacent layers are linked through O—H...O=C hydrogen bonds involving the carboxylic acid OH and carbonyl groups

Chloridobis(1,10-phenanthroline-κ2N,N′)copper(II) chlorido(1,10-phenanthroline-κ2N,N′)(pyridine-2,6-dicarboxylato-κ3O2,N,O6)manganate(II) methanol monosolvate

The title complex, [CuCl(C12H8N2)2][Mn(C7H3NO4)Cl(C12H8N2)]·CH3OH, consists of discrete [CuCl(phen)2]+ cations (phen is 1,10-phenanthroline), [MnCl(pydc)(phen)]− anions (H2pydc is 2,6-pyridine-2,6-dicarboxylic acid) and one methanol solvent molecule of crystallization per asymmetric unit. It should be noted, that a solvent-masking procedure as implemented in OLEX2 [Dolomanov et al. (2009). J. Appl. Cryst. 42, 339–341] was used to remove the electronic contribution from one disordered solvent molecule, presumably methanol. Only the atoms used in the refined model are reported in chemical formula and related values. The CuII ion is five-coordinated by two phenanthroline ligands and one chloride ion in a distorted trigonal–bipyramidal geometry. The dihedral angle between the phen ligands is 65.21 (5)°. The MnII ion is six-coordinated by one Cl atom, two N atoms from a phen ligand, as well one N atom and two O atoms from pydc in a distorted octahedral coordination geometry, with cis angles ranging from 72.00 (8) to 122.07 (8)° and trans angles ranging from 143.98 (8) to 163.15 (6)°. In the crystal, C—H...O, O—H...O and C—H...Cl hydrogen bonds, cation–anion π–π interactions between the phen ring systems with centroid–centroid distances in the range 3.881 (34)–4.123 (36) Å, as well as cation–cation, anion–anion π–π interactions between the phen rings with centroid–centroid distances in the range 3.763 (4)–3.99 (5) Å and pydc rings with centroid–centroid distances 3.52 (5) Å link the various components

Hybrid compound based on diethylenetriaminecopper(ii) cations and scarce V-monosubstituted β-octamolybdate as water oxidation catalyst

Herein, we report on a new hybrid compound (NH4){[Cu(dien)(H2O)2]2[β-VMo7O26]}·1.5H2O (1), where dien = diethylenetriamine, containing an extremely rare mixed-metal pseudo-octamolybdate cluster. An ex situ EPR spectroscopy provided insights into the formation of paramagnetic species in reaction mixture and in solution of 1. The magneto-structural correlations revealed weak antiferromagnetic exchange interactions between the [Cu(dien)]2+ cations transmitted by intermolecular pathways. The cyclic voltammetry showed the one-electron process associated with the Cu3+/Cu2+ oxidation followed by the multi-electron catalytic wave due to water oxidation with a faradaic yield of 86%. The title compound was thus employed in homogeneous water oxidation catalysis using tris(bipyridine)ruthenium photosensitizer. At pH 8.0, efficiency of the catalytic system attained 0.19 turnovers per second supported by the relatively mild water oxidation overpotential of 0.54 V

Copper-containing hybrid compounds based on extremely rare [V2Mo6O26]6- POM as water oxidation catalysts

Herein, we report two approaches to the synthesis of heterometallic complexes (NH4)(2n)(H(2)en)(n){[Cu(en)(2)][alpha-V2Mo6O26]}center dot 4nH(2)O (1), (NH4)(2){[Cu(dien)(H2O)](2)[alpha-V2Mo6O26]}center dot 5H(2)O (2) and (NH4)(2){[Cu(dien)(H2O)](2)[alpha-V2Mo6O26]}center dot 8H(2)O (3) that have been employed in homogeneous photochemical oxidation of water to dioxygen. In these hybrid metalorganic-inorganic compounds, copper-containing complex fragments are covalently bound to the rare vanadium-disubstituted alpha-octamolybdate cluster. They exhibit variable catalytic activity controlled by the local coordination environment of copper reaching a notably high turnover frequency of 0.24 s(-1) for 3 in combination with a relatively low water oxidation overpotential. The complexes have been also used as precursors for the preparation of mixed oxide phases that have proven to be active heterogeneous water oxidation catalysts