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1.
P. C. Mandal D. K. Bardhan S. N. Bhattacharyya 《Journal of Radioanalytical and Nuclear Chemistry》1995,191(2):349-359
Reactions of carbonate radical (CO3
–), generated by photolysis or by radiolysis of a carbonate solution with nickel(II)-iminodiacetate (Ni(II)IDA) were studied at pH 10.5 and ionic strength (I)==0.2 mol·dm–3. The stable product arising from the ligand degradation in the complex is mainly glyxalic acid. Time-resolved spectroscopy and transient kinetics were studied using flash photolysis. From the kinetic data it was suggested that the carbonate radical initially reacts with Ni(III)IDA with a rate constant (2.4±0.4)·106 dm3·mol–1·s–1 to form a Ni(II)IDA species which, however, undergoes a first-order transformation (k=2.7·102·s–1) to give a radical intermediate of the type Ni(II)RNHCHCO
2
–
) which rapidly forms an adduct containing a Ni–C bond. This adduct decays very slowly to give rise to glyoxalic acid. From a consideration of equilibrium between Ni(II)IDA and Ni(III)IDA, the one electron reduction potential for the Ni(III)IDA/Ni(II)IDA couple was determined to be 1.467 V. 相似文献
2.
A. V. Lobanov E. N. Golubeva E. M. Zubanova M. Ya. Mel’nikov 《High Energy Chemistry》2009,43(5):384-390
The product composition and the principles of photochemical transformations of tetrahexylammonium tetrachlorocuprate [(RH)4N+]2[CuIICl4]2− (RH = C6H13) in 2-chlorobutane at 77 K have been found out by ESR spectroscopy. It has been shown that the photolysis of [(RH)4N+]2 [CuIICl4]2− results in the formation of alkyl radicals (R⊙), presumably, anions [CuICl3]2− and organic copper(II) compounds {CuIIR}. A reduction in the quantum yield of primary photolysis products during the reaction, nonequivalence of the quantum yield
of the buildup of paramagnetic photolysis products to that of [CuIICl4]2− consumption, and a decrease in the total number of paramagnetic particles in the system during the photolysis have been revealed.
A photolysis mechanism involving both photochemical and thermal processes is proposed. 相似文献
3.
Peroxydisulfate (PDS) oxidizes N,N′-ethylenebis(isonitrosoacetyleacetoneimine)copper(II) complex, CuIIL, to the corresponding copper(III) complex, [CuIIIL]+. The kinetic runs were performed in the presence of EDTA to scavenge any trace metal impurities. The kinetics of the reaction
at constant pH, ionic strength, and temperature obeys the rate law d[CuIIIL]/dt = 2k
2[CuIIL][S2O8
2−] with k
2 having a value of (8.85 ± 0.32) × 10−2 M−1 s−1 at μ = 0.30 M and T = 25.0 °C. The rate constant k
2 is not affected by variation of pH over the range 3.60–5.20. The second order rate constant is also unaffected by changing
ionic strength. The values of k
obs were determined over the temperature 25.0–40.0 °C range. The enthalpy of activation, ∆H*, and entropy of activation, ∆S*, have been calculated as 34.9 ± 0.5 kJ mol−1 and −173.3 ± 11.4 J K−1 mol−1, respectively. The kinetics of this reaction, as far as we know, is the first evidence that copper(III) is the likely reactive
species in copper catalyzed PDS oxidation reactions. 相似文献
4.
The CuII-mediated oxidation of promazine by dioxygen to form promazine 5-oxide was studied in the presence of a large excess of dioxygen,
CuII-halides (Cl−, Br−) and H+ ions using u.v.–vis and ESR spectroscopies. The first step is a fast reaction between promazine and CuII-halides leading to the production of a stable promazine radical with much higher yield in bromide than chloride media. ESR
results provide clear evidence for the formation of this radical. In the second step the cation radical is oxidized by dioxygen
to a dication hydrolyzing to promazine 5-oxide. The promazine-superoxide complex, concentration of which is determined by
steady-state approximation, is postulated as a significant intermediate resulting from the reduction of dioxygen by the cation
radical. The final product, promazine 5-oxide, is formed via a spontaneous and a CuII-assisted reaction path way. CuII controls the reaction rate through: (i) oxidation of promazine to the promazine radical, (ii) acting as a scavenger of superoxide,
and (iii) slow oxidation of the promazine radical in the parallel reaction. The rate is independent of [H+], linearly dependent on [O2] and only slightly dependent on [CuII] within the excess concentration range of the CuII complexes used. Mechanistic consequences of all these results are discussed. 相似文献
5.
Adrian Topolski Monika Lipiska Przemysaw Kita Joanna Winiewska 《Transition Metal Chemistry》2008,33(7):843-847
The formation of CuII–Br–FeIII-type heterobimetallic complexes was observed spectrophotometrically, given the non-additivity of the spectra from the copper(II)
and iron(III) complexes. The kinetics of the oxidation of promazine radical (ptz+•) to promazine 5-oxide, by iron(III) bromides, copper(II) bromides, and a mixture of these complexes in acidic aqueous solutions,
have been studied using UV–Vis spectroscopy at I = 1.0 M (H+, Cu2+, Fe3+, Br−) and T = 318 K. Copper(II) inhibits the oxidation of the promazine radical to promazine sulfoxide using iron(III) complexes. A rate
retardation effect, characterized by the dependence of the pseudo second-order rate constant (k
II) on the copper(II) concentration k
II = a/(1 + b[CuII]), can be rationalized as a result of CuII–Br–FeIII-type heterobimetallic complex formation. 相似文献
6.
Tao Song Corey N. W. Lam Dominic C. M. Ng Galina Orlova Julia Laskin De-Cai Fang Ivan K. Chu 《Journal of the American Society for Mass Spectrometry》2009,20(6):972-984
The dissociation of [CuII(L)His]•2+ complexes [L=diethylenetriamine (dien) or 1,4,7-triazacyclononane (9-aneN3)] bears a strong resemblance to the previously reported behavior of [CuII(L)GGH]•2+ complexes. We have used low-energy collision-induced dissociation experiments and density functional theory (DFT) calculations
at the B3LYP/6-31+G(d) level to study the macrocyclic effect of the auxiliary ligands on the formation of His•+ from prototypical [CuII(L)His]•2+ systems. DFT revealed that the relative energy barriers of the same electron-transfer (ET) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ are very similar, with the ET reactions of [CuII(9-aneN3)His]•2+ leading to the generation of two distinct His•+ species; in contrast, the proton transfer (PT) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ differ considerably. The PT reactions of [CuII(9-aneN3)His]•2+ are associated with substantially higher barriers (>13 kcal/mol) than those of [CuII(dien)His]•2+. Thus, the sterically encumbered auxiliary 9-aneN3 ligand facilitates ET reactions while moderating PT reactions, allowing the formation of hitherto nonobservable histidine
radical cations. 相似文献
7.
Brian N. DiMarco Dmitry E. Polyansky David C. Grills Ping Wang Yutaka Kuwahara Xuan Zhao Etsuko Fujita 《Chemphyschem》2021,22(14):1478-1487
In this work, the differences in catalytic performance for a series of Co hydrogen evolution catalysts with different pentadentate polypyridyl ligands (L), have been rationalized by examining elementary steps of the catalytic cycle using a combination of electrochemical and transient pulse radiolysis (PR) studies in aqueous solution. Solvolysis of the [CoII−Cl]+ species results in the formation of [CoII(κ4-L)(OH2)]2+. Further reduction produces [CoI(κ4-L)(OH2)]+, which undergoes a rate-limiting structural rearrangement to [CoI(κ5-L)]+ before being protonated to form [CoIII−H]2+. The rate of [CoIII−H]2+ formation is similar for all complexes in the series. Using E1/2 values of various Co species and pKa values of [CoIII−H]2+ estimated from PR experiments, we found that while the protonation of [CoIII−H]2+ is unfavorable, [CoII−H]+ reacts with protons to produce H2. The catalytic activity for H2 evolution tracks the hydricity of the [CoII−H]+ intermediate. 相似文献
8.
Christopher M. Lemon Michael Huynh Andrew G. Maher Bryce L. Anderson Dr. Eric D. Bloch Prof. Dr. David C. Powers Prof. Dr. Daniel G. Nocera 《Angewandte Chemie (International ed. in English)》2016,55(6):2176-2180
The ground state electronic structure of copper corroles has been a topic of debate and revision since the advent of corrole chemistry. Computational studies formulate neutral Cu corroles with an antiferromagnetically coupled CuII corrole radical cation ground state. X‐ray photoelectron spectroscopy, EPR, and magnetometry support this assignment. For comparison, CuII isocorrole and [TBA][Cu(CF3)4] were studied as authentic CuII and CuIII samples, respectively. In addition, the one‐electron reduction and one‐electron oxidation processes are both ligand‐based, demonstrating that the CuII centre is retained in these derivatives. These observations underscore ligand non‐innocence in copper corrole complexes. 相似文献
9.
Ali Ourari Kamel Ouari Wahiba Moumeni Lakhdar Sibous Gilles M. Bouet Mustayeen A. Khan 《Transition Metal Chemistry》2006,31(2):169-175
Salicylaldehyde or 5-bromosalicylaldehyde reacted with 2,3-diaminophenol in absolute EtOH in a 2:1 molar ratio to give new
unsymmetrical Schiff bases (H2L). The bases were used as ligands to coordinate Mn(III), Ni(II) and Cu(II) chlorides leading to [MnIIIClL] · EtOH and [MIIL] or [MIIL] · 2H2O (M = Ni or Cu) complexes. Their structures were determined using mass spectroscopy, IR, u.v.–vis and 1H-n.m.r. The cyclic voltammetry in acetonitrile showed irreversible waves for both ligands. Under the same experimental conditions,
the complexes exhibited mainly the non-reversible reduction of the Ni(II) or Cu(II) ion to Ni(0) or Cu(0), while the reduction
of Mn(III) to Mn(II) was found to be a quite reversible phenomenon. 相似文献
10.
Tarafder M. Tofazzal H. Ali Manaf A. Wee D. Juan Azahari Kasbollah Silong Sidik Crouse Karen A. 《Transition Metal Chemistry》2000,25(4):456-460
Several new complexes of a tridentate ONS Schiff base derived from the condensation of S-benzyldithiocarbazate with salicylaldehyde have been characterised by elemental analyses, molar conductivity measurements
and by i.r. and electronic spectra. The Schiff base (HONSH) behaves as a dinegatively charged ligand coordinating through
the thiolo sulphur, the azomethine nitrogen and the hydroxyl oxygen. It forms mono-ligand complexes: [M(ONS)X], [M=NiII, CuII, CrIII, SbIII, ZnII, ZrIV or UVI with X = H2O, Cl]. The ligand produced a bis-chelated complex of composition [Th(ONS)2] with ThIV. Square-planar structures are proposed for the NiII and CuII complexes. Antimicrobial tests indicate that the Schiff base and five of the metal complexes of CuII, NiII, UVI, ZnII and SbIII are strongly active against bacteria. NiII and SbIII complexes were the most effective against Pseudomonas aeruginosa (gram negative), while the CuII complex proved to be best against Bacillus cereus (gram positive bacteria). Antifungal activities were also noted with the Schiff base and the UVI complex. These compounds showed positive results against Candida albicans fungi, however, none of them were effective against Aspergillus ochraceous fungi. The Schiff base and its zinc and antimony complexes are strongly active against leukemic cells (CD50 = 2.3–4.3 μg cm−3) while the copper, uranium and thorium complexes are moderately active (CD50 = 6.9–9.5 μg cm−3). The nickel, zirconium and chromium complexes were found to be inactive.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
A. A. Semioshkin P. V. Petrovskii D. Gabel B. Brellochs V. I. Bregadze 《Russian Chemical Bulletin》1998,47(5):950-955
The sodium salt of [B12H12]2− dianion reacts with carboxylic acid halides to give a mixture of B-acylated product [B12H11COR]2− and an unstable intermediate, the latter undergoing hydrolysis to form [B12H11OH]2−. The ratio of the products formed depends on the nature of the radical R. The reaction mechanism was studied by NMR spectroscopy.
A number of novel [B12H11COR]2− compounds were synthesized; their structures were confirmed by NMR and IR spectral data.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 980–985, May, 1998. 相似文献
12.
Ki-Young Choi Min-Ah Whang Han-Hyoung Lee Kyu-Chul Lee Moon-Jip Kim 《Transition Metal Chemistry》2004,29(7):792-796
Two mononuclear copper(II) complexes [Cu(L)(NO2)](ClO4) (1) and [Cu(L)(MO4)]2· 5H2O (2) (L = 1,3,10, 12,16,19-hexaazatetracyclo[17,3,1,112.16,04.9]tetracosane) have been synthesized and their structures determined. Both compounds show a distorted square-pyramidal geometry with the two secondary and two tertiary amines of the macrocycle and one ligand coordinated at the axial position. Cyclic voltammetry of the complexes gives two one-electron waves corresponding to CuII/CuIII and CuII/CuI processes. The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature of the organic ligands. 相似文献
13.
The reaction of [M(L)]Cl2 · 2H2O (M = Ni2+ and Cu2+, L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane) with 1,1-cyclobutanedicarboxylic acid (H2-cbdc) generates 1D and 2D hydrogen-bonded infinite chains [Ni(L)(H-cbdc−)2] (1) and [Cu(L)(H-cbdc−)2] (2). (H-cbdc− = cyclobutane-1-carboxylic acid-1-carboxylate). These complexes have been characterized by X-ray crystallography, spectroscopy,
and cyclic voltammetry. The crystal structure of 1 shows a distorted octahedral coordination geometry around the nickel(II) ion, with four secondary amines and two oxygen atoms
of the H-cbdc− ligand at the trans position. In 2, the coordination environment around the central copper(II) ion shows a Jahn–Teller distorted octahedron with four Cu–N bonds
and two long Cu–O distances. The cyclic voltammogram of the complexes undergoes two one-electron waves corresponding to MII/MIII and MII/MI processes. The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature
of the axial H-cbdc− ligand. 相似文献
14.
Summary Manganese(III) acetate was prepared by the electrolytic oxidation of Mn(OAc)2 in aqueous AcOH. The electro-generated manganese(III) species was characterised by spectroscopic and redox potential studies.
The kinetics of oxidation of pyridoxine (PRX) by manganese(III) in aqueous AcOH were investigated and is first order with
respect to [MnIII]. The effects of varying [MnIII], [PRX], added manganese(II), pH and added anions such as AcO−, F−, Cl− and ClO
inf4
sup−
and SO
inf4
sup2−
were studied. The rate decreased slowly with increasing [H+] up to 0.2 mol dm−3 and increased steeply thereafter. The orders in [PRX] and [MnII] were unity and inverse fractional, respectively, in both low and high [H+] ranges. The dependence of reaction rate on temperature was studied and activation parameters were computed from Arrhenius
and Eyring plots. A mechanism consistent with the observed results is proposed and discussed. 相似文献
15.
Wu Feng Deng Nansheng E. M. Glebov I. P. Pozdnyakov V. P. Grivin V. F. Plyusnin N. M. Bazhin 《Russian Chemical Bulletin》2007,56(5):900-903
The formation of MV•+ radical cations was observed upon the laser flash photolysis of the iron(III) tartrate complex [FeIIITart]+ (1) in the presence of methyl viologen (MV2+). The rate constants of the reactions involving MV•+ were measured. The intramolecular electron trans-fer to form FeII and escape of the organic radical to the solvent bulk upon the photolysis of 1 were proposed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 866–869, May, 2007. 相似文献
16.
Choi Ki-Young Jeon Yong-Man Lee Kyu-Chul Choi Suk-Nam Kim Moon-Won Lim Hae-Hwan Kim Moon-Jip 《Transition Metal Chemistry》2004,29(4):405-410
Tetradentate Schiff-base carboxylate-containing ligands, bis(2-pyridylmethyl)amino-3-propionic acid (Hpmpa) and bis(2-pyridylmethyl)amino-4-butyric acid (Hpmba), react with CuCl2 to give rise to the mononuclear complexes [Cu(Hpmpa)Cl]Cl · 2H2O (1) and [Cu(Hpmba)Cl2]· H2O (2). These complexes have been characterized by X-ray crystallography, spectroscopic and cyclic voltammetry. Crystal structure of (1) shows that the copper(II) ion has a distorted square-pyramidal geometry with the three nitrogen atoms of the Hpmpa ligand and one chloride anion occupying the basal plane and an oxygen atom from the carboxylate group coordinating the axial position. In (2), the coordination environment around the copper(II) ion reveals a distorted square-pyramids with three nitrogen atoms of the Hpmba ligand and one chloride anion that comprise the basal plane, whereas the apical position is filled by the chloride anion. Cyclic voltammetry of the complexes gives two one-electron waves corresponding to CuII/CuIII and CuIII/CuI processes. The electronic spectra and redox potentials of the complexes are influenced significantly by the N-pendant carboxylate groups. 相似文献
17.
The octahedral complex, [CoIII(HL)]·9H2O (H4L = (1,8)-bis(2-hydroxybenzamido)-3,6-diazaoctane) incorporating bis carboxamido-N-, bis
sec-NH, phenolate, and phenol coordination has been synthesized and characterized by analytical, NMR (1H, 13C), e.s.i.-Mass, UV–vis, i.r., and Raman spectroscopy. The formation of the complex has also been confirmed by its single
crystal X-ray structure. The cyclic voltammetry of the sample in DMF ([TEAP] = 0.1 mol dm−3, TEAP = tetraethylammonium perchlorate) displayed irreversible redox processes, [CoIII(HL)] → [CoIV(HL)]+ and [CoIII(HL)] → [CoII(HL)]− at 0.41 and −1.09 V (versus SCE), respectively. A slow and H+ mediated isomerisation was observed for the protonated complex, [CoIII(H2L)]+ (pK = 3.5, 25 °C, I = 0.5 mol dm−3). H2Asc was an efficient reductant for the complex and the reaction involved outer sphere mechanism; the propensity of different
species for intra molecular reduction followed the sequence: [{[CoIII(HL)],(H2Asc)}–H]− <<< {[CoIII(H2L)],(H2Asc)}+ < {[CoIII(HL)],(H2Asc)}. A low value (ca. 3.7 × 10−10 dm3 mol−1 s−1, 25 °C, I = 0.5 mol dm−3) for the self exchange rate constant of the couple [CoIII(HL)]/[CoII(HL)]− indicated that the ligand HL3− with amido (N-) donor offers substantial stability to the CoIII state. HSO3− and [CoIII(HL)] formed an outer sphere complex {[CoIII(HL)],(HSO3−)}, which was slowly transformed to an inner sphere S-bonded sulfito complex, [CoIII(H2L)(HSO3)] and the latter was inert to reduction by external sulfite but underwent intramolecular SIV → CoIII electron transfer very slowly.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
18.
Gadde Ramachandraiah 《Journal of Chemical Sciences》1995,107(4):385-391
The interaction of azide (N
3
−
) ion, at pH 5.3 with [RuIII(EDTA) (H2O)]− (EDTA = ethylenediaminetetraacetate) was studied in aqueous solution by polarography and cyclic voltammetry. The product,
[RuIII(EDTA)(N3)]2− showed a multi-electron reduction step, which is polarographically reversible but, cyclic voltammetrically irreversible,
in the potential range − 0.1 to − 0.2 V vs SCE. This reduction step, which was different from the one-electron reduction step
of [RuIII(EDTA)(H2O)]; (E1/2 = −0.113V vs SCE) was assigned to the reduction of the coordinated azide ion to ammonia by the irreversible transfer of electrons
from Hg-electrode via ruthenium metal. Azide, at pH 5.3, was reduced, electrolytically, for the first time, to ammonia at
Hg-pool cathode mediated by [RuIII(EDTA) (N3)]2−. The turnover number with respect to the formation of ammonia (moles of ammonia per mole of ruthenium per hour) was obtained
from the constant potential electrolysis data. On the basis of experimental observations, a probable mechanism has been proposed
for the electrocatalytic reduction of azide to ammonia in aqueous solution. 相似文献
19.
Ahmed E. Fazary Erzalina Hernowo Artik Elisa Angkawijaya Tse-Chuan Chou Chih Hung Lin Mohamed Taha Yi-Hsu Ju 《Journal of solution chemistry》2011,40(12):1965-1986
The complexation equilibria of L-norleucine and gallic acid were studied in aqueous solutions at 25.00 °C and ionic strength
0.15 mol⋅dm−3 (NaNO3), by means of potentiometry and spectrophotometry. The ferric (FeIII), chromium (CrIII), and cupric (CuII) complexing abilities of L-norleucine and gallic acid, along with their overall stability constants, were obtained with the
HYPERQUAD 2008 program from the potentiometric data. The concentration distributions of the various complex species in solution
were evaluated and discussed. UV–visible spectroscopic measurements were carried out to give qualitative information about
the composition of the complexes formed in these solutions. The cytotoxic activities of the binary and ternary metal complexes
of L-norleucine and gallic acid were tested and evaluated against HEp-2 (human laryngeal carcinoma), Daoy (human medulloblastoma),
MCF-7 (human breast adenocarcinoma), and WiDr (human colon adenocarcinoma) tumor cell lines. Also, their antioxidant activities
were examined by free radical scavenging assay. 相似文献
20.
Zou Jianzhong Hu Xiaodong Duan Chenying Xu Zheng You Xiaozeng Mak Thomas C. W. 《Transition Metal Chemistry》1998,23(4):477-480
Reaction of either K3[Fe(CN)6] or K4[Fe(CN)6] with a macrocyclic CuII complex, [Cu(teta)](ClO4)2 (teta = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacylotetradecane), in aqueous solution gave the same product as shown by spectroscopic and physicochemical characterisation. The crystal structure of the complex shows that it is a one-dimensional linear chain type heterobinuclear FeIII–CuII polymer. The unit is composed of a [Cu(teta)(H2O)2]2+ cationic complex, a FeIII–CuII alternate linear chain unit, a ClO
4
–
ion and four water molecules. The Cu atom is coordinated in a distorted octahedral arrangement by four nitrogen atoms from one teta ligand and two nitrogen atoms of the bridging cyanide groups. The Cu—N bond distances involving the cyanide bridges, 2.522(7) and 2.608(7)Å, respectively, indicate weak antiferromagnetic interactions between the FeIII and CuII atoms. 相似文献