Search results for "COPPER"
showing 10 items of 3029 documents
Synthesis and characterization of a 1,8-difunctionalized dissymmetrical cyclam copper(II) complex bearing pyridylmethyl and N,N-dimethylcarbamoylmeth…
2001
The new dissymmetrical ligand 1-(N,N-dimethylcarbamoylmethyl)-8-(2-pyridylmethyl)-4,11-dimethyl-1,4,8,11-tetraazacyclotetradecane, 5, was synthesized and the physicochemical properties of its copper(II) complex, [CuII(5)](ClO4)2·CH3CN, were determined. UV–Vis, IR, ESR experiments, and X-ray analysis of [CuII(5)](ClO4)2·CH3CN were carried out. The X-ray structure of [CuII(5)](ClO4)2·CH3CN revealed a distorted square pyramid with the four coordinating nitrogen atoms of the macrocycle lying in the basal position. Curiously, the fifth ligand is the N,N-dimethylcarbamoylmethyl group through the oxygen atom and not the pyridylmethyl moiety.
Heterotetranuclear Complexes of Reduced and Non-reduced Bridging 1,2,4,5-Tetrazine Ligands with 1,1′-Bis(diphenylphosphanyl)-ferrocene-copper(I)
2015
The complexes {(μ-bptz)[Cu(dppf)]2}(BF4)2 [(1)(BF4)2] [bptz = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine, dppf = 1,1′-bis(diphenylphosphanyl)ferrocene] and {(μ-bpztz)[Cu(dppf)]2}(PF6)2 [(2)(PF6)2] [bpztz = 3,6-bis(2-pyrazinyl)-1,2,4,5-tetrazine] contain two redox-active heterodinuclear FeIICuI moieties, bridged by a redox-active ligand. A crystal structure determination of (1)(BF4)2·2CH2Cl2 confirms the non-reduced aromatic nature of the bridge, in contrast to previous results on dicopper(I) complexes of bptz. Facile one-electron reduction produces the radical complexes {(μ-bptz)[Cu(dppf)]2}+ (1+) and {(μ-bpztz)[Cu(dppf)]2}+ (2+), which could be isolated [as (1)(BF4)] and studied by variable freq…
Isomerization and rearrangement of (E)- and (Z)-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole: evidence for a “new” type of acid-catalysis …
2008
A kinetic investigation in methanol of the title reaction has evidenced the occurrence of two processes: the 1-E1-Z isomerization and the rearrangement of the (Z)-isomer into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole (1-Z T). The latter reaction is in line with the ability of the (Z)-phenylhydrazones of 3-benzoyl-1,2,4-oxadiazoles to undergo the so called mononuclear rearrangement of heterocycles (MRH). The occurrence of both the examined reactions is dependent on a Lewis-acid-catalysis. The obtained results have shown the possibility of a ‘new’ type of acid-catalysis (bifunctional catalysis by Lewis salts) in the MRH. This catalysis operates through a completely different me…
Extended structures of copper(II) complexes with 2-di1H-2-imidazolylmethylmalonate (DIMMAL), a versatile bis(imidazole)–bis(carboxylate) ligand: Solu…
2008
Abstract Copper(II) complexes of 2-di1H-2-imidazolylmethylmalonate (DIMMAL) have been studied by potentiometric methods. The data revealed that the CuHL 2 - and CuL 2 2 - species are prevalent in the studied pH range. Moreover, this paper reports the synthesis, structure solution and spectroscopic characterization of two new DIMMAL containing complexes, (NH4)2[Cu(DIMMAL)2] · 4H2O (1) and [Cu(DIMMAL)(en)(H2O)] · 5H2O (2). The structure of compound 1 consists of centrosymmetric mononuclear anionic [Cu(DIMMAL)2]2− units, NH 4 + cations and lattice water molecules, in which DIMMAL2− acts as a tridentate ligand through two imidazole nitrogen atoms and one oxygen atom from a carboxylate group. Th…
CO2 Fixation by Cu2+ and Zn2+ complexes of a terpyridinophane aza receptor. Crystal structures of Cu2+ complexes, pH-metric, spectroscopic, and elect…
2006
The synthesis of the terpyridinophane-type polyamine 2,6,9,12,16-pentaaza[17]-(5,5' ')-cyclo-(2,2':6',2' ')-terpyridinophane heptahydrobromide tetrahydrate (L.7HBr.4H2O) is described. L presents six protonation constants with values in the range 9.21-3.27 logarithmic units. L interacts with Cu2+ and Zn2+ forming in both cases, neutral, protonated, and hydroxylated mono- and binuclear complexes whose constants have been calculated by potentiometry in 0.15 M NaClO4 at 298.1 K. The crystal structures of the compounds [Cu(HL-carb)(H2O)](ClO4)3.2H2O (1) and [Cu2(H2L)(CO3)]2(ClO4)8.9H2O (2) have been solved by X-ray diffraction. In 1, the metal center presents square pyramidal geometry. The base …
Copper complexes of polyaza[n]cyclophanes and their interaction with DNA and RNA
2001
Abstract The complexation properties of Cu 2+ ions with the cyclophane receptors 2,6,9,13-tetraaza[14]metacyclophane ( L1 ), 2,6,10,13,17,21-hexaaza[22]metacyclophane ( L2 ) and 2,6,10,13,17,21-hexaaza[22]paracyclophane ( L3 ) are presented. Formation of mononuclear complexes in the case of L1 and of mono- and binuclear complexes in the case of the hexaaazcyclophane ligands L2 and L3 is observed. The coordination numbers around each Cu 2+ in the binuclear complexes involve at most three nitrogen donors for each metal ion. Cyclophanes L1 – L3 and several acyclic polyamine ligands are tested for their affinity towards double-stranded nucleic acid models of RNA and DNA. The binding affinity of…
Synthesis, structure, and nuclease properties of several binary and ternary complexes of copper(II) with norfloxacin and 1,10 phenantroline
2007
Three new binary Cu(II) complexes of norfloxacin have been synthesized and characterized. We also report the synthesis, characterization and X-ray crystallographic structures of a new binary compound, [Cu(HNor)(2)]Cl(2).2H(2)O (2) and two new ternary complexes norfloxacin-copper(II)-phen, [Cu(Nor)(phen)(H(2)O)](NO(3)).3H(2)O (4), and [Cu(HNor)(phen)(NO(3))](NO(3)).3H(2)O (5). The structure of 2 consists of two crystallographically independent cationic monomeric units of [Cu(HNor)(2)](2+), chloride anions, and uncoordinated water molecules. The Cu(II) ion is placed at a center of symmetry and is coordinated to two norfloxacin ligands which are related through the inversion center. The struct…
Structural analysis and magnetic properties of the copper(II) dicyanamide complexes [Cu2(dmphen)2(dca)4], [Cu(dmphen)(dca)(NO3)] and [Cu(4,4′-dmbpy)(…
2004
Abstract The preparation, crystal structures and magnetic properties of three copper(II) compounds of formulae [Cu2(dmphen)2(dca)4] (1), [Cu(dmphen)(dca)(NO3)]n (2) and [Cu(4,4′-dmbpy)(H2O)(dca)2] (3) (dmphen=2,9-dimethyl-1,10-phenanthroline, dca=dicyanamide and 4,4′-dmbpy=4,4′-dimethyl-2,2′-bipyridine) are reported. The structure of 1 consists of discrete copper(II) dinuclear units with double end-to-end dca bridges whereas that of 2 is made up of neutral uniform copper(II) chains with a single symmetrical end-to-end dca bridge. Each copper atom in 1 and 2 is in a distorted square pyramidal environment: two (1) or one (2) nitrile-nitrogen atoms from bridging dca groups, one of the nitrogen…
Two new supramolecular architectures of singly phenoxo-bridged copper(II) and doubly phenoxo-bridged manganese(II) complexes derived from an unusual …
2009
International audience; Two new coordination complexes {[(L)Cu2('-L)(NO3)(CH3OH)0.3(H2O)0.7]·NO3}[Cu(L)(NO3)(CH3OH)] (1) and [Mn2(-L)2(H2O)(1-N3)2(CH3OH)] (2) derived from (E)-N-(2-hydroxy-3-methoxybenzylidene)acetohydrazide [LH] have been synthesized. The new potentially tetradentate ONOO donor hydrazone ligand [LH] has shown considerable metal ion selective phenoxo bridging in 1 and 2. It has coordinated copper(II) ions in its tridentate as well as in tetradentate fashion whereas for manganese(II) ions it solely showed its tetradentate character. In 1 the two adjacent pentacoordinate copper(II) centers are connected by a rare single phenoxo linkage of the hydrazone ligand whereas 2 is a d…
Tetrakis(1-ethyl-1H-1,2,4-triazole-κN4)bis(nitrato-κO)copper(II) and bis(nitrato-κO)tetrakis(1-propyl-1H-1,2,4-triazole-κN4)copper(II)
2005
The copper(II) environments for tetrakis(1-ethyl-1,2,4-triazole)dinitratocopper(II), [Cu(NO 3 ) 2 (C 4 H 7 N 3 ) 4 ], and tetrakis-(1-propyl-1,2,4-triazole)dinitratocopper(II), [Cu(NO 3 ) 2 (C 5 -H 9 N 3 ) 4 ], are distorted square bipyramidal. Both structures are centrosymmetric, with the copper(II) ions located at inversion centers coordinated by four N atoms of four triazole molecules and by two O atoms of two nitrate ions in an elongated octahedral geometry. This elongation is a result of the Jahn-Teller effect. The largest distortion is that of the N-Cu-O angles, which differ from 90 by 5.68 (10)° in the ethyl and 5.59 (8)° in the propyl derivative.