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Complex Ions (complex + ion)
Selected AbstractsMössbauer Investigation of Peroxo Species in the Iron(III),EDTA,H2O2 SystemEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005Virender K. Sharma Abstract The reaction of a diiron(III),EDTA complex with H2O2 in alkaline medium is studied by Mössbauer spectroscopy in conjunction with the rapid-freeze/quench technique in order to identify possible intermediate species during the formation and decomposition of the purple (EDTA)FeIII(,2 -O2)3, complex ion. Starting from the six-coordinate [FeIIIEDTA], species at acidic pH, it is demonstrated that mononuclear complexes formed at a pH of about 1 are convert into the diiron(III),EDTA complex [(EDTA)FeIII -O-FeIII(EDTA)]4, upon raising the pH to around 10.4. H2O2 reacts with the diiron(III) complex to give peroxide/hydroperoxide related adducts. Initially, the reaction tears apart the dimers to form a peroxo adduct, namely the seven-coordinate mononuclear [(EDTA)FeIII(,2 -O2)]3,, which is stable only at very high pH. The decomposition of this peroxo adduct gives two new species, which are reported for the first time. The Mössbauer parameters of these species suggest a six-coordinate ,-peroxodiiron(III) complex [(EDTA)FeIII -(OO)-FeIII(EDTA)]4, and a seven-coordinate ,-hydroxo-,-peroxodiiron(III) complex [(EDTA)FeIII -(OO)(OH)-FeIII(EDTA)]5,. A badly resolved, extremely broad component is observed in the Mössbauer spectra during the conversion of the monomer to dimeric peroxo species, which may be attributed to the short-lived [(EDTA)FeIII -OO]3, or [(EDTA)FeIII -OOH]2, intermediate species. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Kinetics of Fe(II) reduction of cis -halogeno(dodecylamine) bis(ethylenediamine)- cobalt(III) complex ion in aqueous solutionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2006K. Santhakumar Kinetics of reduction of the surfactant complex ions, cis -chloro/bromo (dodecylamine)bis(ethylenediamine)cobalt(III) by iron(II) in aqueous solution was studied at 303, 308, and 313 K by spectrophotometry method under pseudo-first-order conditions, using an excess of the reductant. The second-order rate constant remains constant below critical micelle concentration (cmc), but increases with cobalt(III) concentration above cmc, and the presence of aggregation of the complex itself alters the reaction rate. The rate of reaction was not affected by the added [H+]. Variation of ionic strength (,) influences the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction of Fe2+ (aq) with cobalt(III) complex proceeds by the inner-sphere mechanism. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 98,105, 2006 [source] The role of Bi3+ -complex ion as the stabilizer in electroless nickel plating processAICHE JOURNAL, Issue 4 2009K. Wang Abstract Bi3+ -complex ion is presented here as a less toxic stabilizer for use in electroless nickel plating (ENP) to replace the existing Pb2+ ion stabilizer. The asymmetric derivatives of EDTA are identified to be a type of coordination ligands that can combine with Bi3+ ions to form soluble complexes in the acidic ENP solution. In the ENP system studied the Bi3+ -complex ion displays a critical stabilizer concentration of about 10,5 mol/L, that is, the percolation concentration over which the ENP rate drops sharply. Besides the experimental measurement, deposition rates of both Ni and P are also simulated by using a kinetic model that has been derived from the double electric layer theory. The Bi3+ -complex ion, behaving like conventional Pb2+ ion, stabilizes ENP bath through the chemical replacement reaction at the surface of Ni deposition layer and results in a passive plating surface. This investigation also verifies the properties of the EN deposit, which are insignificantly affected by the length of service time of the plating solution by employing Bi3+ -complex ion stabilizer. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Stability of Anion Binding with Monomers of a Cationic SurfactantCHEMPHYSCHEM, Issue 6 2008Anna Jakubowska Dr. Competitive binding: Electrospray ionisation mass spectrometry is used to probe the binding ability of different anions with a cationic surfactant. Bond strengths are estimated from plots of the intensity of the peak assigned to a given complex ion in the mass spectrum versus the cone voltage applied to induce the abstraction of the counterions from the monomers (see graph). [source] A Novel Self-assembled Supramolecular Complex {[Cu(n) (en)2·H2O] [Cu(I)2(CN)4]}n with Honeycomb-like Structure and Its Adsorption PropertiesCHINESE JOURNAL OF CHEMISTRY, Issue 12 2002Xiao-Ping Shen Abstract A novel supramolecular complex {[Cu(n)(en)2·H2O]·[Cu(I)2(CN)4]}n (en = ethylenediamine), in which the cyanide-bridged Cu(I) forms the honeycomb-like skeleton host and the Cu(n) complex ion [Cu(en)2·H2O]2+ is encapsulated in the center of the channel cavity of the skeleton, was synthesized by two different methods. The complex was also characterized by elemental analysis, ICP analysis, IR spectra and thermal analysis. The adsorption and desorption studies of the complex indicate that H2O and NH3 can be desorbed and re-adsorbed without collapse of the channel structure of the supramolecule. [source] Kinetics of Fe(II) reduction of cis -halogeno(dodecylamine) bis(ethylenediamine)- cobalt(III) complex ion in aqueous solutionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2006K. Santhakumar Kinetics of reduction of the surfactant complex ions, cis -chloro/bromo (dodecylamine)bis(ethylenediamine)cobalt(III) by iron(II) in aqueous solution was studied at 303, 308, and 313 K by spectrophotometry method under pseudo-first-order conditions, using an excess of the reductant. The second-order rate constant remains constant below critical micelle concentration (cmc), but increases with cobalt(III) concentration above cmc, and the presence of aggregation of the complex itself alters the reaction rate. The rate of reaction was not affected by the added [H+]. Variation of ionic strength (,) influences the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction of Fe2+ (aq) with cobalt(III) complex proceeds by the inner-sphere mechanism. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 98,105, 2006 [source] Detection of preformed macrocyclic nickel complex ions using two-step electrospray ionization mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 3 2005Chang-Nan Chen [source] Gas-phase binding of non-covalent protein complexes between bovine pancreatic trypsin inhibitor and its target enzymes studied by electrospray ionization tandem mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2001Victor J. Nesatyy Abstract The potential of electrospray ionization (ESI) mass spectrometry (MS) to detect non-covalent protein complexes has been demonstrated repeteadly. However, questions about correlation of the solution and gas-phase structures of these complexes still produce vigorous scientific discussion. Here, we demonstrate the evaluation of the gas-phase binding of non-covalent protein complexes formed between bovine pancreatic trypsin inhibitor (BPTI) and its target enzymes over a wide range of dissociation constants. Non-covalent protein complexes were detected by ESI-MS. The abundance of the complex ions in the mass spectra is less than expected from the values of the dissociation constants of the complexes in solution. Collisionally activated dissociation (CAD) tandem mass spectrometry (MS/MS) and a collision model for ion activation were used to evaluate the binding of non-covalent complexes in the gas phase. The internal energy required to induce dissociation was calculated for three collision gases (Ne, Ar, Kr) over a wide range of collision gas pressures and energies using an electrospray ionization source. The order of binding energies of the gas-phase ions for non-covalent protein complexes formed by the ESI source and assessed using CAD-MS/MS appears to differ from that of the solution complexes. The implication is that solution structure of these complexes was not preserved in the gas phase. Copyright © 2001 John Wiley & Sons, Ltd. [source] Activation of large lons in FT-ICR mass spectrometryMASS SPECTROMETRY REVIEWS, Issue 2 2005Julia Laskin Abstract The advent of soft ionization techniques, notably electrospray and laser desorption ionization methods, has enabled the extension of mass spectrometric methods to large molecules and molecular complexes. This both greatly extends the applications of mass spectrometry and makes the activation and dissociation of complex ions an integral part of these applications. This review emphasizes the most promising methods for activation and dissociation of complex ions and presents this discussion in the context of general knowledge of reaction kinetics and dynamics largely established for small ions. We then introduce the characteristic differences associated with the higher number of internal degrees of freedom and high density of states associated with molecular complexity. This is reflected primarily in the kinetics of unimolecular dissociation of complex ions, particularly their slow decay and the higher energy content required to induce decomposition,the kinetic shift (KS). The longer trapping time of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) significantly reduces the KS, which presents several advantages over other methods for the investigation of dissociation of complex molecules. After discussing general principles of reaction dynamics related to collisional activation of ions, we describe conventional ways to achieve single- and multiple-collision activation in FT-ICR MS. Sustained off-resonance irradiation (SORI),the simplest and most robust means of introducing the multiple collision activation process,is discussed in greatest detail. Details of implementation of this technique, required control of experimental parameters, limitations, and examples of very successful application of SORI-CID are described. The advantages of high mass resolving power and the ability to carry out several stages of mass selection and activation intrinsic to FT-ICR MS are demonstrated in several examples. Photodissociation of ions from small molecules can be effected using IR or UV/vis lasers and generally requires tuning lasers to specific wavelengths and/or utilizing high flux, multiphoton excitation to match energy levels in the ion. Photodissociation of complex ions is much easier to accomplish from the basic physics perspective. The quasi-continuum of vibrational states at room temperature makes it very easy to pump relatively large amounts of energy into complex ions and infrared multiphoton dissociation (IRMPD) is a powerful technique for characterizing large ions, particularly biologically relevant molecules. Since both SORI-CID and IRMPD are slow activation methods they have many common characteristics. They are also distinctly different because SORI-CID is intrinsically selective (only ions that have a cyclotron frequency close to the frequency of the excitation field are excited), whereas IRMPD is not (all ions that reside on the optical path of the laser are excited). There are advantages and disadvantages to each technique and in many applications they complement each other. In contrast with these slow activation methods, the less widely appreciated activation method of surface induced dissociation (SID) appears to offer unique advantages because excitation in SID occurs on a sub-picosecond time scale, instantaneously relative to the observation time of any mass spectrometer. Internal energy deposition is quite efficient and readily adjusted by altering the kinetic energy of the impacting ion. The shattering transition,instantaneous decomposition of the ion on the surface,observed at high collision energies enables access to dissociation channels that are not accessible using SORI-CID or IRMPD. Finally, we discuss some approaches for tailoring the surface to achieve particular aims in SID. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:135,167, 2005 [source] Diastereochemical differentiation of bicyclic diols using metal complexation and collision-induced dissociation mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2009Jaana M. H. Pakarinen Metal complex formation was investigated for di- exo -, di- endo - and trans -2,3- and 2,5-disubstituted trinorbornanediols, and di- exo - and di- endo - 2,3-disubstituted camphanediols using different divalent transition metals (Co2+, Ni2+, Cu2+) and electrospray ionization quadrupole ion trap mass spectrometry. Many metal-coordinated complex ions were formed for cobalt and nickel: [2M+Met]2+, [3M+Met]2+, [M,H+Met]+, [2M,H+Met]+, [M+MetX]+, [2M+MetX]+ and [3M,H+Co]+, where M is the diol, Met is the metal used and X is the counter ion (acetate, chloride, nitrate). Copper showed the weakest formation of metal complexes with di- exo -2,3-disubstituted trinorbornanediol yielding only the minor singly charged ions [M,H+Cu]+, [2M,H+Cu]+ and [2M+CuX]+. No clear differences were noted for cobalt complex formation, especially for cis -2,3-disubstituted isomers. However, 2,5-disubstituted trinorbornanediols showed moderate diastereomeric differentiation because of the unidentate nature of the sterically more hindered exo -isomer. trans -Isomers gave rise to abundant [3M,H+Co]+ ion products, which may be considered a characteristic ion for bicyclo[221]heptane trans -2,3- and trans -2,5-diols. To differentiate cis -2,3-isomers, the collision-induced dissociation (CID) products for [3M+Co]2+, [M+CoOAc]+, [2M,H+Co]+ and [2M+CoOAc]+ cobalt complexes were investigated. The results of the CID of the monomeric and dimeric metal adduct complexes [M+CoOAc]+ and [2M,H+Co]+ were stereochemically controlled and could be used for stereochemical differentiation of the compounds investigated. In addition, the structures and relative energies of some complex ions were studied using hybrid density functional theory calculations. Copyright © 2009 John Wiley & Sons, Ltd. [source] Polymorphism in the nitrate salt of the [Mn(acetylacetonate)2(H2O)2]+ ionACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2010A. R. Biju The crystallization of [Mn(acac)2(H2O)2]+ from solutions containing excess nitrate leads to the formation of four polymorphs. All polymorphs contain two different types of complex ions, one containing essentially coplanar acac ligands and the other in which the two acac ligands together assume a chair conformation. Molecular modelling using DFT (density-functional theory) calculations shows that the coplanar conformation is the electronically stable one. The hydrogen bonding between the trans -water molecules and the nitrate ion produces a one-dimensional chain of 12-membered rings, which are further organized into a two-dimensional network via a lattice water molecule. Lattice-energy calculations have been carried out to compare the stabilities of the four polymorphs. [source] Structure-forming components in crystals of ternary and quaternary 3d -metal complex fluoridesACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2003E. V. Peresypkina Crystallochemical analysis and classification were performed for 139 ternary and quaternary complex fluorides with the general formula M1nM2mM3F6, belonging to 33 structure types. Using coordination sequences and the uniformity criterion the structure-forming ionic sublattices or their combinations were found, which are responsible for the formation of stable periodic frameworks. Analysis of structure-forming motifs allows the interpretation of the crystal structures of complex fluorides as close packings of F ions with M1, M2 and M3 cations, partially occupying tetrahedral and octahedral voids, or as the packings of [M3F6] complex ions with M1 and M2 countercations in the voids. Cationic sublattices are noted to play an essential role, while forming crystal structures of complex fluorides. Relationships between the composition of structure-forming sublattices, the composition of compounds, and the size and charge of ions belonging to the sublattices were analysed under normal conditions, with thermal and high-pressure polymorphic transitions. Rules were formulated to predict the crystal structures of complex fluorides with a given chemical composition. [source] Hydrogen bonding and structure of Ba2Ru2Cl10O·10H2OACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2007Sihem Boufas Dibarium ,-oxido-bis[pentachloridoruthenate(IV)] decahydrate, Ba2Ru2Cl10O·10H2O, has been prepared from ruthenium(III) chloride and barium chloride in hydrochloric acid. It crystallizes in the monoclinic system (space group C2/c). The structure consists of alternating layers of [Ru2Cl10O]4, and [Ba(H2O)7]2+ complex ions along the a direction. The O atom bonded to ruthenium occupies the 4e site, with symmetry, while the other atoms occupy general 8f sites. The overall structure is held together by O,H...O hydrogen bonds and O,H...Cl dipole,dipole interactions. [source] | |||||||||||||||||||||||||