N,N′-Dimethyl­ethylenediammonium dioxalatocuprate(II)

The asymmetric unit of the title salt, (C4H14N2)[Cu(C2O4)2], consists of one complex anion and two cationic half-mol­ecules, the other halves being generated by inversion symmetry. The CuII atom in the anion is coordinated by two bidentate oxalate ligands in a distorted square-planar geometry. Inter­molecular hydrogen bonds, involving the NH groups as donors and O atoms as acceptors, are observed, which lead to the formation of a three-dimensional network structure

Bis(N,N′-dimethyl­ethylenediammonium) tris­(oxalato-κ2 O 1,O 2)cobaltate(II) dihydrate: an ion-pair complex

The CoII ion in the title complex, (C4H14N2)2[Co(C2O4)3]·2H2O, is coordinated by three oxalate ions, resulting in a distorted octa­hedral geometry. Two uncoordinated water mol­ecules are present in asymmetric unit. Inter­molecular N—H⋯O and O—H⋯O hydrogen bonds between the different entities stabilize the crystal structure

4,6-Dimethyl-2-thioxo-1,2-dihydro­pyrimidin-3-ium chloride–thio­urea (1/1)

In the title compound, C6H9N2S+·Cl−·CH4N2S, the 4,6-di­methyl-2-thioxo-1,2-dihydro­pyrimidin-3-ium cation is proton­ated at one of the pyrimidine N atoms. The cations are bridged by the chloride anions through a pair of N—H⋯Cl hydrogen bonds. The amino groups of each thio­urea adduct inter­act with the chloride anions through a pair of N—H⋯Cl hydrogen bonds and the S atom of another thio­urea adduct through a pair of N—H⋯S hydrogen bonds. These inter­actions result in a layered hydrogen-bonded network propagating parallel to the bc plane. Except for two H atoms, all atoms are on special positions

1-(Thio­phen-2-yl)ethanone thio­semi­carbazone

The title compound, C7H9N3S2, crystallizes with two unique mol­ecules in the unit cell, both present as thio­semicarbazide tautomers. The mol­ecules differ principally in the dihedral angles between the thio­phene ring planes and the planes through the non-H atoms of the hydrazinecarbothio­amide units, viz. 9.80 (8)° for one mol­ecule and 19.37 (7)° for the other. The hydrazinecarbothio­amide units are reasonably planar, with r.m.s. deviations of 0.001Å for each of the mol­ecules. In the crystal, N—H⋯S hydrogen bonds link like mol­ecules into R 2 2(8) inversion dimers. A three-dimensional network structure is generated by additional N—H⋯S hydrogen bonds and weak C—H⋯S contacts between the unique mol­ecules

Chlorido[N′-(2-oxidobenzil­idene)acetohydrazide-κ2 O,N′,O′]copper(II) dihydrate

In the title complex, [Cu(C9H9N2O2)Cl]·2H2O, prepared from the Schiff base ligand N′-(2-hydroxy­benzil­idene)aceto­hydrazide and copper(II) chloride, the CuII atom is coord­inated by two O atoms and one N atom from the ligand and by a Cl atom in a distorted square-planar geometry. The two donor O atoms of the tridentate Schiff base ligand are in a trans arrangement. In the crystal structure, there is an extensive inter­molecular hydrogen-bonding network; N—H⋯O, O—H⋯O and O—H⋯Cl inter­actions, involving the uncoordinated water mol­ecules, lead to the formation of a two-dimensional network parallel to the ab plane

Synthesis and X-ray crystallography of (1R,3aR,7aR)-1-((S)-1-((2R,5S)-5-(3-hydroxypentan-3-yl)tetrahydrofuran-2-yl)ethyl)-7a-methyloctahydro-4H-inden-4-one

The crystal of the title compound, C21H36O3 contains an oxolane ring, and six defined stereocenters which are unambigously established by the crystallography study. A three dimensional supramolecular architecture is ensured by hydrogen bonds from the hydroxy group which is both engaged in inter (O-H···O2) and intramolecular C-H···O-H) hydrogen bonds. Weak C-H···O=C hydrogen bonds are involved also into the consolidation of the network

The synthesis and the reactivity of arene ruthenium oxalato complexes

This article outlines the reactions of the well known [RuCl(η6-p-cymene)]2(μ-η4-C2O4) and [RuCl(η6-p-cymene)(η2-dppm)][PF6] ruthenium complexes with C2O4(Me4N)2 in the mol ratios 1:1 and 2:1. While the 2:1 ratio reaction led to the sole and expected binuclear product {[Ru(η6-p-cymene)(η2-dppm)]2(μ-η2-C2O4)}[PF6]2, the reaction also afforded the unexpected mononuclear complex [RuCl(η2-C2O4)(η6-p-cymene)][Me4N]. This can also be obtained in improved yield by reacting [RuCl2(p-cymene)]2 with C2O4[Me4N]2 in a 1:1 mol ratio. Surprisingly, when [RuCl(η6-p-cymene)]2(μ-η4-C2O4) was reacted with an equimolar amount of the ligand dppm, the expected complex {[Ru(η6-p-cymene)]2(μ-η4-C2O4)(μ-dppm)}[PF6]2 was accompanied by [RuCl(η6-p-cymene)(η2-dppm)][PF6] in an inseparable solid mixture. KEY WORDS: Ruthenium, Arene, p-cymene, Mesitylene, Oxalate, bis-(Dipenylphosphino)methane  Bull. Chem. Soc. Ethiop. 2008, 22(2), 207-217

COPPER(II) COMPLEXES OF o-VANILLIN ACETYLHYDRAZONE (H2L) AND THE SINGLE-CRYSTAL X-RAY STRUCTURE OF [{Cu(HL)(H

A hydrazonic ligand, o-vanillin acetylhydrazone (H2L) has been prepared and used as chelating agent towards copper(II) ion. The ligand acts like a tridentate ligand in the monodeprotonated (HL-) and dideprotonated (L2-) states. Monoanionic complexes [{Cu(HL)(H2O)}2]•2BF4 and [{Cu(HL)(Hpz)(H2O)}]•NO3 have been isolated. After neutralization the complex [{Cu(L)}2].5/2H2O is obtained. These complexes have been characterized by a range of physicochemical and spectroscopic studies. The X-ray crystal structure of the mononuclear complex [{Cu(HL)(Hpz)(H2O)}]•NO3 was also determined. This crystal is orthorombic with the space group I222, a = 13.417(3), b = 22.662(6), c = 22.518(5) Å, α = β = γ = 90° and Z = 8. The copper ion has a square-pyramidal geometry with the basal donors atoms from the tridentate ligand (ONO) and the pyrazole (N), the apical position being occupied by a coordinated water molecule weakly linked to the copper(II) center. The binuclear complexes exhibit interesting magnetic properties. KEY WORDS: Copper(II) complexes, Tridentate ligand, o-Vanillin acetylhydrazone, X-Ray crystal structure Bull. Chem. Soc. Ethiop. 2006, 20(1), 35-43

Synthesis and X-ray structure of the dysprosium(III) complex derived from the ligand 5-chloro-1,3-diformyl-2-hydroxybenzene-bis-(2-hydroxybenzoylhydrazone) [Dy2(C22H16ClN4O5)3]

The title compound [Dy2(C22H16ClN4O5)3](SCN)3(H2O)(CH3OH) has been synthesized and its crystal structure determined by single X-ray diffraction at room temperature. The two nine coordinated Dy(III) are bound to three macromolecules ligand through the phenolic oxygens of the p-chlorophenol moieties, the nitrogen atoms and the carbonyl functions of the hydrazonic moieties. The phenolic oxygen atoms of the 2-hydroxybenzoyl groups are not bonded to the metal ions. In the bases of the coordination polyhedra the six Dy-N bonds are in the range 2.563(13)-2.656(13) Å and the twelve Dy-O bonds are in the range 2.281(10)-2.406(10) Å. KEY WORDS: Dysprosium(III) complex, 5-Chloro-1,3-diformyl-2-hydroxybenzene-bis-(2-hydroxybenzoylhydrazone), Crystal structure  Bull. Chem. Soc. Ethiop. 2003, 17(2), 167-172

A Volatility Analysis of Agricultural Commodity and Crude Oil Global Markets

The purpose of this study is to provide insights on volatility features of major agricultural commodity global markets. In order to achieve this, we estimate the volatility in the global markets of crude oil and four main agricultural commodities, namely rice, wheat, cotton and coffee over the period 1980:2014. We also investigate the nexus between the volatilities in these global markets. More precisely, we first model the volatility of agricultural commodity and crude oil markets based on the GARCH methodology. Second, we assess the risk in these global markets by the Value-at-Risk technique. Finally, we evaluate the co-movements between returns in agricultural commodity and crude oil markets by the copula methodology. Our empirical findings reveal that, unlike in the financial market, upside shocks in the agricultural market tend to increase volatility more than downside shocks do. In addition to that, risk in global agricultural commodity markets turned out to be high and little evidence in favor of interdependence between these markets is found. Moreover, the co-movement between agricultural commodity market risk and oil prices is detected for recent years only and little evidence is found for the whole sample period