Search results for "Alate"
showing 10 items of 695 documents
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…
Automatic in-tube SPME and fast liquid chromatography: A cost-effective method for the estimation of dibuthyl and di-2-ethylhexyl phthalates in envir…
2007
A 80-cm length commercially available capillary coated with 95% polydimethylsiloxane and 5% polydiphenylsiloxane (TBR-5) was employed to carry out on-line extraction and preconcentration of dibuthyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) in the chromatographic system. The coated capillary was placed between the sample injection loop and the injection needle of an autosampler. Variables affecting the automatic in-tube solid-phase microextraction (SPME) were optimized. A Genesis C(18) (5 cm x 4.6 mm i.d., 4 microm particle size) was employed as analytical column. The achieved limits of detection by use of diode array detection were 1 and 2.5 microg L(-1), respectively. The propo…
On-line in-tube solid phase microextraction-capillary liquid chromatography method for monitoring degradation products of di-(2-ethylhexyl) phthalate…
2014
Abstract The main di-(2-ethylhexyl) phthalate (DEHP) degradation products, (2-ethylhexyl) phthalate (MEHP), diethyl phthalate (DEP) and dibutyl phthalate (DBP), have been tested. The proposed cost-effective method combines on-line, in-tube solid-phase micro extraction (IT-SPME) in in-valve configuration and capillary liquid chromatography with UV diode array detection (Cap-LC-DAD). Acidification of the samples at pH 3 improved markedly the estimation of MEHP. Aliquots of 4 mL of acidified water samples were directly processed. After sample loading, the analytes were desorbed with the mobile-phase and transferred to the monolithic capillary column. Satisfactory linearity and precision, absen…
Supercritical fluid extraction and high performance liquid chromatography determination of homosalate in lipsticks
2001
Supercritical fluid extraction of homosalate is reported for the first time. Extraction parameters such as pressure, time of extraction, use of modifier, temperature and sample mass were studied. The proposed method was assayed for the extraction of homosalate in sunscreen lipsticks. Efficient recoveries were obtained after 5 min of dynamic extraction with supercritical CO2 and 15% ethanol as modifier at 300 bar and 60°C, flow rate 4 mL min−1. Extracts were dissolved in ethanol, and homosalate determined by HPLC using water—acetic acid—ethanol mobile phase and flow rate of 1 mL min−1. UV detection was at 309 nm using homosalate in ethanol solutions as standards, limit of detection 4 μg mL−1…