Search results for "Oxalate"
showing 10 items of 215 documents
[Cr(phen)(ox)2]-: a versatile bis-oxalato building block for the design of heteropolymetallic systems. Crystal structures and magnetic properties of …
2000
The new complexes of formula AsPh4[Cr(phen)(ox)2]·H2O (1), [NaCr(phen)(ox)2(H2O)]·2H2O (2) and {[Cr(phen)(ox)2]2[Mn2(bpy)2(H2O)2(ox)]}·6H2O (3) (AsPh4=tetraphenylarsonium cation; phen=1,10-phenanthroline; ox=oxalate dianion; bpy=2,2′-bipyridine) have been prepared and characterized by single-crystal X-ray diffraction. The structure of 1 consists of discrete [Cr(phen)(ox)2]− anions, tetraphenylarsonium cations and uncoordinated water molecules. The chromium environment in 1 is distorted octahedral with Cr–O bond distances between 1.959(3) and 1.947(3) A and Cr–N bonds of 2.083(4) and 2.072(4) A. The angles subtended at the chromium atom by the two oxalates are 83.6(2) and 83.3(1)° whereas th…
Hexafluorophosphate and Oxalate Complexes of 4-Methoxy-2-(5-methoxy-3-methyl-pyrazol-1-yl)-6-methylpyrimidine with Co(II), Ni(II), and Cu(II)
1986
Abstract Complexes of Co(II), Ni(II) and Cu(II) with the title ligand, L, have been prepared and characterized through elemental analysis, conductance measurements, electronic and infrared spectra, and magnetic measurements. For all hexafluorophosphate complexes monomeric species with CuL2 2+ and ML3 2+ (M=Co,Ni,Cu) have been isolated. In the oxalate complexes the C2O4 = group act as a bidentate bridge to form compounds with probable dimeric (copper(II)) or polymeric (cobalt(II) and nickel(II)) structures.
Binuclear Nickel(II) Complexes Based on Bridging Oxalate and Pseudohalides as Peripheral Ligands: Synthesis, Crystal Structure, DFT Calculations and …
2000
Nickel(II) molecular complexes were obtained by water displacement reactions of [{Ni(dien)(H2O)}2(μ-ox)]Cl2 and the corresponding pseudohalide. The three nickel(II) compounds [{Ni(N3)(dien)}2(μ-ox)] (1), [{Ni(NCO)(dien)}2(μ-ox)] · H2O (2) and [{Ni(NCS)(dien)}2(μ-ox)] (3) are almost isostructural. The structure determinations reveal the presence of a binuclear complex with C2h symmetry, where the oxalate ligand is coordinated in a bis(bidentate) fashion to the twofold related nickel atoms. The distorted octahedral environment of each nickel atom is completed by the three nitrogen atoms of the diethylenetriamine ligand in a fac arrangement and one nitrogen atom from a pseudohalide ligand. Mag…
Synthesis, X‐ray Crystal Structure and Magnetic Properties of Oxalato‐Bridged Copper( II ) Complexes with 2,3‐Bis(2‐pyridyl)pyrazine, 2,3‐Bis(2‐pyrid…
2004
Five oxalate-containing copper(II) complexes of formula [Cu(dpq)(H2O)(ox)]·5H2O (1), [Cu(dpp)(H2O)(ox)]·H2O (2), [Cu(bpz)(ox)]n (3), [Cu2(dpp)2(H2O)2(NO3)2(ox)]·4H2O (4) and [Cu2Cl2(bpz)2(H2O)2(ox)][Cu(bpz)(H2O)2(ox)]·2H2O (5) [dpq = 2,3-bis(2-pyridyl)quinoxaline; dpp = 2,3-bis(2-pyridyl)pyrazine; bpz = 2,2′-bipyrazine; ox = oxalate] were prepared and their structures were determined by X-ray diffraction on single crystals. Complexes 1 and 2 are discrete mononuclear complexes with oxalate and dpq (1)/dpp (2) acting as bidentate ligands. Complex 3 is a neutral oxalato-bridged (2,2′-bipyrazine)copper(II) chain where the oxalate adopts a bidentate/monodentate coordination mode, whereas 4 is an…
[Cr(bpym)(C2O4)2]− in designing heterometallic complexes. Crystal structures and magnetic properties of PPh4[Cr(bpym)(C2O4)2]·H2O and [Ag(bpym)][Cr(C…
2002
Abstract The preparation, crystal structure and magnetic properties of PPh 4 [Cr(bpym)(C 2 O 4 ) 2 ]·H 2 O ( 1 ) and [Ag(bpym)][Cr(C 2 O 4 ) 2 (H 2 O) 2 ]·2H 2 O ( 2 ) (C 2 O 4 2− =oxalate dianion, bpym=2,2′-bipyrimidine and PPh 4 + =tetraphenylphosphonium cation) are described. The structure of 1 is made up of discrete (2,2′-bipyrimidine)bis(oxalato)chromate(III) anions, teraphenylphosphonium cations and uncoordinated water molecules. The structure of 2 consists chains of univalent silver cations bridged by bis-chelating 2,2′-bypyrimidine, cis -diaquabis(oxalato)chromate(III) anions and crystallisation water molecules. The chromium atom in 1 and 2 has a slightly distorted octahedral geom…
Electronic properties and crystal structure of aqua (mepirizole-oxalato)copper(II)monohydrate: [Cu(C11H14N4O2)C2O4·H2O]H2O
1988
Abstract A Cu(ll) complex with mepirizole: 4-methoxy-2-(5-methoxy-3-methyl-pyrazoll-yl)-6-methylpyrimidine (L) and oxalate as ligands with the formula [CuL(C2O4)(H2O)]·H2O has been synthesized. The crystal structure has been determined by X-ray diffraction analysis: monoclinic, space group P21/n, Z = 4, a = 7.707(1), b = 14.951(3), c = 14.986(2) A,β = 92.40(2)°, V = 1725.2(8) A3, Dm = 1.61(1) g cm−3, Dc = 1.62 g cm−3, R = 0.032 and Rw = 0.035 for 2016 observed reflections. The CuN2O2O′chromophore can be described as square pyramidal strongly distorted towards trigonal bipyramidal. The basal coordination positions are occupied by the two oxygen atoms of the bidentate oxalate group, the coord…
Enhancing the Magnetic Coupling of Oxalato-Bridged ReIV2MII (M = Mn, Co, Ni, and Cu) Trinuclear Complexes via Peripheral Halide Ligand Effects
2011
Four heterotrinuclear Re(IV)(2)M(II) compounds of general formula (NBu(4))(2)[{Re(IV)Br(4)(μ-ox)}(2)M(II)(Him)(2)] [NBu(4)(+) = tetra-n-butylammonium cation, ox = oxalate, Him = imidazole; M = Mn (1), Co (2), Ni (3), and Cu (4)] have been synthesized by using the novel mononuclear complex [Re(IV)Br(4)(ox)](2-) as a ligand toward divalent first-row transition metal ions in the presence of imidazole. Compounds 1-4 are isostructural complexes whose structure contains discrete trinuclear [{Re(IV)Br(4)(μ-ox)}(2)M(II)(Him)(2)](2-) anions and bulky NBu(4)(+) cations. The Re and M atoms are six-coordinated: four peripheral bromo and two oxalate-oxygens (at Re), and two cis-coordinated imidazole mol…
[Cr(AA)(C2O4)2]− and [Cu(bpca)]+ as building blocks in designing new oxalato-bridged CrIIICuII compounds [AA=2,2′-bipyridine and 1,10-phenanthroline…
2003
Abstract The monouclear complex PPh4[Cr(bipy)(ox)2]·H2O (1) and the heterodinuclear compounds [Cu(bpca)(H2O)Cr(bipy)(ox)2]·2.5H2O (2) and [Cu(bpca)(H2O)Cr(phen)(ox)2]·2H2O (3) [PPh4+=tetraphenylphosphonium cation, bpca=bis(2-pyridylcarbonyl)amide anion, ox=oxalate dianion, bipy=2,2′-bipyridine and phen=1,10-phenanthroline] have been synthesized and characterized by single-crystal X-ray diffraction. Discrete [Cr(bipy)(ox)2]− mononuclear anions and tetraphenylphosphonium cations are present in 1 whereas the structures of 2 and 3 are made up neutral oxalato-bridged bimetallic CrIIICuII units. The chromium environment is distorted octahedral in the three complexes: two nitrogen atoms from a bi…
Selective determination of ammonium in water based on HPLC and chemiluminescence detection
2005
Abstract A selective and sensitive method has been developed for liquid chromatographic determination of ammonium in water samples. The analyte is derivatized with Dansyl Chloride prior to injection into HPLC. Optimal solution derivatization conditions have been established. The dansyl derivative is separated with the aid of a chromatographic column and post-column mixed with peroxyoxalate (TCPO) and H 2 O 2 in order to perform chemiluminescence detection. The detection limit achieved is 8 μg/L and linear response from 0.027 to 0.750 mg/L of ammonium was obtained. Ammonium ion was determined within 2.4 min under optimum chromatographic conditions. The method is fast, and near 10 derivatized…
Simultaneous quantification of the main organic acids and carbohydrates involved in tomato flavour using capillary zone electrophoresis
2002
A capillary zone electrophoresis (CZE) procedure for the simultaneous determination of the major organic acids (oxalate, malate and citrate) and carbohydrates (fructose, glucose and sucrose) in Lycopersicon fruits is reported. Comparison of this method with routine HPLC methods indicates that the CZE method offers several attractive features (speed, resolution, sensitivity and cost) which significantly improve the determination of these compounds. Detection limits were better than 1.6 µg ml−1 for organic acids and from 13 to 24 µg ml−1 for carbohydrates; repeatabilities were better than 2.1% for migration times and between 1.4 and 7.3% for peak areas. The proposed protocol is very useful to…