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This application note describes a correlative Raman-scanning electron microscope (SEM) investigation of a lithium-ion battery cathode before and after hundreds of charge cycles. The technique provides an exceptionally detailed chemical and structural analysis of degradation processes on the nanoscale., Lithium-ion battery technology is the key enabler of the current revolution in transportation and energy. Improving the performance of Li-ion cells is among the highest priorities in contemporary research and [...]

Synthesesof 1,11-bis(salicylaldimine)-3,6,9-trithiaundecane ([H.sub.2]L1), 1,11-bis(salicylaldimine)-6-oxa-3,9- dithiaundecane ([H.sub.2]L2), and 1,8-bis(salicylaldimine)-3,6-dithiaundecane ([H.sub.2]L3), their nickel complexes [Ni(L1)]*[H.sub.2]O(I), [Ni(HL2)][OAc] (II), [[Ni(L3)-HOAc].sub.2][Ni(L3)-2HOAc]*3[H.sub.2]O (III), [Ni(HL1-sal)][Cl.sub.2]*[H.sub.2]O(IV), [Ni(HL2-sal)][Cl.sub.2]*C[H.sub.3]OH (V), [Ni(L3-sal)Cl]*[H.sub.2]O(VI), [{[Ni(HL1-sal)][Br.sub.2]}.sub.2][Ni(L1-sal)]Br}*[H.sub.2]O(VII), [{[Ni(HL2- sal)][Br.sub.2]}.sub.2]{[Ni(L2-sal)]Br}*2C[H.sub.3]OH (VIII), {[Ni(HL3-sal)Br]Br}[Ni(L3-sal)Br]*2C[H.sub.3]OH (IX), [Ni(HL3-sal)Br]Br*C[H.sub.3]OH (X), [Ni(HL3)Br]*2[H.sub.2]O(XI), [[Ni(HL1)].sub.2][[B[F.sub.4]].sub.2]*5[H.sub.2]O(XII), [[Ni(HL2)].sub.2][[B[F.sub.4]].sub.2]*3[H.sub.2]O(XIII), [Ni(HL3)MB[F.sub.4]]2*C[H.sub.3]CN (XIV), and [Ni(HL3)MB[F.sub.4]]2*3[H.sub.2]O (XV) and their cobalt complexes [Co(L1-sal)][[B[F.sub.4]].sub.2] (XVI), [Co(L2)][OAc]*3[H.sub.2]O(XVII), [Co(L3)][OAc]*3[H.sub.2]O(XVIII), [Co(L3)][B[F.sub.4]](XIX), and [Co(L3-sal)(C[H.sub.3]OH)][[B[F.sub.4]].sub.2]*C[H.sub.3]OH (XX) are reported. Single crystal X-ray structural studies for III, XIV, XVI, and XIX are described. Cyclic voltammogramsof the ligands andof I, II, III, VII, VIII, X, XIV, and XIX are discussed. Electronic spectraof the ligands and complexes are discussed. Key words: cobalt and nickel complexes, thioether, salicylaldimine ligands, X-ray structure, cyclic voltammetry, UV-vis spectra. On decrit les syntheses du 1,11-bis(salicylaldimine)-3,6,9-trithiaundecane ([H.sub.2]L1), 1,11-bis(salicylaldimine)-6- oxa3,9-dithiaundecane ([H.sub.2]L2) et du 1,8-bis(salicylaldimine)-3,6-dithiaundecane ([H.sub.2]L3), de leurs complexes de nickel [Ni(Ll)]- [H.sub.2]O (I), [Ni(HL2)][OAc] (II), [[Ni(L3)-HOAc].sub.2][Ni(L3)-2HOAc]*3[H.sub.2]O(III), [Ni(HL1-sal)][Cl.sub.2]*[H.sub.2]O(IV), [Ni(HL2-sal)][Cl.sub.2]-C[H.sub.3]OH (V), [Ni(L3-sal)Cl]*[H.sub.2]O(VI), {[Ni(HL1-sal)][Br.sub.2]M[Ni(L1-sal)]Br}*[H.sub.2]O(VII), {[Ni(HL2- sal)][Br.sub.2]h{[Ni(L2-sal)]Br}*2C[H.sub.3]OH (VIII), {[Ni(HL3-sal)Br]Br}2[Ni(L3-sal)Br]*2C[H.sub.3]OH (IX), [Ni(HL3-sal)Br]Br*C[H.sub.3]OH (X), [Ni(HL3)Br]*2[H.sub.2]O(XI), [Ni(HL1)MB[F.sub.4]]2*5[H.sub.2]O(XII), [Ni(HL2)2[[B[F.sub.4]].sub.2]*3[H.sub.2]O(XIII), [Ni(HL3MB[F.sub.4]]2- C[H.sub.3]CN (XIV) et [Ni(HL3)2MB[F.sub.4]]2-3[H.sub.2]O (XV) ainsi que de leurs complexes de cobalt [Co(L1-sal)][[B[F.sub.4]].sub.2] (XVI), [Co(L2)][OAc]-3[H.sub.2]O(XVII), [Co(L3)][OAc]-3[H.sub.2]O (XVIII), [Co(L3)][B[F.sub.4]](XIX) et [Co(L3-sal)(C[H.sub.3]OH)][[B[F.sub.4]].sub.2]*C[H.sub.3]OH (XX).on decrit les structures des composes III, XIV, XVI et XIX telles que determinees par diffraction des rayons-X.on discute des resultatsobtenus par voltamperometrie cyclique des ligands I, II, III, VII, VIII, X, XIV et XIX.on discute aussi des spectres electroniques des ligands et des complexes. Mots-cles : complexes du cobalt et du nickel, thioether, ligands de la salicylaldimine, structure par diffraction des rayons X, voltamperometrie cyclique, spectres UV-visible. [Traduit par la Redaction], Introduction Metal complexes of salicylaldimine ligands continue to be of interest for several reasons, not the least of which is their potential for use in a variety of applications such [...]

It is for the first time that orientational probability distribution function for CO transiently docked in myoglobin (Mb) and Hb is established. The ordered protein structure around the active site of the enzyme has a selectivity even for small ligands.

Crystalline materials are isolated and characterized from mixing silver carborane salts Ag(CB11H12) or Ag-[Co(C2B9H11)(sub 2)] with bridging alkanedinitriles. The structure of [Ag-(malonitrile)2](BF4), is determined to have an unusual chiral diamondoid structure with a skewed 2-fold interpenetration.

Byline: A. P. Smirnova (1), V. V. Chernysh (1), M. A. Proskurnin (1) Abstract: Thermal lens spectrometry was used to study the dissociation kinetics of diethyldithiocarbamate complexes of copper(II), cobalt(III), and nickel(II) as a function of pH in the presence of chloride and sulfate ions. It is shown that, as distinct from conventional spectrophotometric and potentiometric measurements, the reversible dissociation of the test complexes and the irreversible oxidation of the ligand can be studied separately (at a level of n x 10.sup.--8--n x 10.sup.--6 M) using thermal lens spectrometry. Because of work in more dilute solutions and due account of the kinetic features of the systems in question, thermal lens spectrometry provides a higher accuracy of the determination of stability constants for diethyldithiocarbamate complexes of copper(II), cobalt(III), and nickel(II). The adsorption of the diethyldithiocarbamate complexes in question from water--ethanol solutions (1 : 3) on Silasorb C.sub.18 silica is studied, and the adsorption constants are determined. The limits of detection of copper(II), cobalt(III), and nickel(II) diethyldithiocarbamates obtained in extraction--thermal-lens determination are n x 10.sup.--8 M. Author Affiliation: (1) Department of Chemistry, Moscow State University, Vorob'evy gory, Moscow, 117234, Russia Article History: Registration Date: 06/10/2004

Electron paramagnetic resonance (EPR) study on Co(II)corrins Cob(II)ester(1+) and base-off B12r(2+) provides the first direct evidence for axial solvent ligation in polar solvents. EPR forms an excellent tool to analyze subtle changes in the electronic structure of Co(super II)-corrin systems, especially when they are supported by density functional computations.

Electronic absorption, circular dichroism, magnetic CD and resonance Raman spectroscopic techniques are used to probe the electronic excited states of Co(super 3)+cbl species that differ with respect to their axial ligand. Adocobinamide is included to probe the effect of the lower axial ligand on the electronic properties of Cbls.

A number of cobalt complexes of substituted polypyridine ligands are synthesized and investigated as possible alternatives to the volatile and corrosive iodide/triiodide redox couple commonly used as an electron-transfer mediator in dye-sensitized solar cells (DSSCs). Cyclic voltammetric studies reveal a dramatic surface dependence of the heterogeneous electron-transfer rate, which is surprisingly different for gold, carbon, and platinum electrodes.

Research has been conducted on the glutathionylcobalamin functioning as an intermediate in the biosynthesis of the active B (sub)12 coenzymes adenosylcobalamin and methylcobalamin. The stability of this compound has been examined in comparison to other thionylcobalamins.

This paper describes microelectrode voltammetry measurements of serf-diffusion coefficients and of heterogeneous Co(II/III) electron-transfer rate constants (k(super o)) in undiluted molten salts of three cobalt tris(bipyridine) perchlorate complexes in which the bipyridine ligands are 'tailed' with poly(propylene oxide) and poly(ethylene oxide) oligomers. The self-diffusion coefficients are measured with potential step chronoamperometry and range from 10(super-12) to 10(super -17) cm(super 2)/s, while the quasi-reversible reaction rate constants are measured using cyclic voltammetry and small potential steps and range from 10(super -7) to 10(super -12) cm/s. The k(super o) measurements are unusual in that when rate constants become smaller, the reaction remains quasi-reversible, because of concurrently decreasing self-diffusion rates. The measurements are, furthermore, accomplished in the face of uncompensated resistances that range from mega- to gigaohms, which is made possible by the combination of microelectrode properties and small diffusivities. The melt in which serf-diffusion and k(super o) values are smallest is at a temperature below its nominal glassing transition and in the regime of molecule-scale diffusion profiles.

Research is presented concerning the superparamagnetic properties in CoFe2O4 and MgFe2O4 spinel ferrite nanoparticles. The use of Mossbauer spectroscopy to study the magnetic anisotropy of the nanoparticles is discussed.

Research has been conducted on the copper chaperone for superoxide dismutaes gene. The encoding of the protein that delivers copper ions to copper-zinc superoxide dismutase is described.

Research has been conducted on the organocobalt(III) complexes. The use of EPR spectroscopy in understanding the photolysis mechanism of anaerobic solutions in aprotic solvents is described.

Research has been conducted on the Co (sub)2 {[N(CN) (sub)2] (sub)4 bpym} . H (sub)2 O and M{[N(CN) (sub)2 bpym} . H (sub)2 O (M = Mn, Fe, Co; bpym = 2,2'-bipyrimidine). The synthesis and structural characteristics of the compound are described.

Research has been conducted on the Co-bleomycin coordination chemistry. Nuclear magnetic resonance spectroscopy has been used in investigating Co(II) in Co(II)-bleomycin coordination sphere.

Ab initio calculations of the highest occupied molecular orbitals of several guanine-containing sequences with cobalt ion and benzoyl peroxide are presented.

Research has been conducted on the (super)23 C spin-lattice relaxation rates. The measurements of these rates for Escherichia coli adenylate kinase complexes are presented.

Chemical oxidation of the linear tricobalt compound CO3(dpa)4C12 with NOBF4 yields (Co3(dpa)4C12)+, a one-electron oxidized species.

Research has been conducted on the tetranuclear cobalt(II) cage compound. The union between molecular cages and metal-assembled grids has been investigated.

Catalysis of the hydrolytic removal of the N-terminal formyl group from ribosome-synthesized polypeptides by peptide deformylase is discussed. The ability of the metal ion to ionize the water molecule has been analyzed.

Investigation of the selectivity of guanine oxidation promoted by nickel and cobalt reagents has been conducted by means of Z-DNA structural characteristics. Results demonstrate the possibility of the reagent application to different targets.

Aquation of the chloro pentaamine complexes of chromium(III) and cobalt(III) is discussed. Almost equal activation parameters may or may not arise from a common mechanism and have been investigated. The strongly negative volumes of activation would suggest one shares associative mechanism. Computations of the corresponding reaction coordinates show that a dissociative interchange mechanism works for cobalt(III) and that for chromium(III) there is an associative interchange mechanism. Bond length changes allow reaction mechanism to be determined.

Research has been conducted on the trinucleating ligands. The preparation of these ligands from the hexachlorocyclotriphosphazene reaction with 3,3'-dihydroxy-2,2'-bipyridine is examined.

Research has been conducted on the cationic sulfenacobalt(III) complexes with ligand amines. The reaction of the complexes with hydrated methyldioxorhenium(V) is described.

Research is presented describing the pressure effects on reactant coefficients and electrode reaction rates which can provide evidence for solvent dynamic incursion in nonaqueous systems, without changing the solvent's chemical identity.

The use of a Fourier transform ion cyclotron resonance mass spectrometer to study water clusters of salen transition metal complexes, formed by an electrospray source, is described.

Research is presented demonstrating the combined use of an inelastic neutron scattering study with magnetic susceptibility, specific heat and magnetization measurements on a deuterated sample of K10[Co4(H2O)2(PW9O34)2].22H2O, to investigate the ground state properties of a tetranuclear Co2+ cluster.

Research has been conducted on the macrocyclic cobalt hexaamines. The ability of these hexaamines to reduce the overpotential for hydrogen evolution in aqueous solution is examined.

Research has been conducted on the sigma-bounded organo-iron and -cobalt porphyrins. The examination of these porphyrins as a compound oxidation state function had been carried out.

Research has been conducted on the axial fragment in cobalamins that contain axial S ligand. The structural characterization of this fragment is presented.

Research has been conducted on the phenol-based macrocyclic ligands. Results indicate that they have a salen-like metal-binding site.

Research has been conducted on the tert-butyldimethylsiloxy derivatives treated with Co (sub)2 (CO) (sub)8. Experiments with the cobalt-complexed enynes exposed to Pauson-Khand conditions are discussed.

Research was conducted to examine the synthesis of P-N-P bidentate ligands, assess their pi-acceptor properties in the complexes obtained from phenylacetylene-dicobalt hexacarbonyl and to describe the reactivity of the complexes in the Pauson-Khand reaction. Experimental results show that the important bond distances and angles in the ligands agree with literature values. Findings may help in the design of effective chiral ligands for a new approach to asymmetric Pauson-Khan reactions.

Research was conducted to examine five polymeric framework arrays that result from the reaction of bis(amides) of the type CH3CONH(CH2)(sub n)NHCOCH3 with a range of manganese(II) and cobalt(II) salts using X-ray crystallography. The objective was to determine whether representative members of HBMA complexes had network structures. Results of preparations of other transition-metal complexes with the ligands are described.

Research was conducted to examine the reactivity and structure of phosphate monoesters coordinated to the dinuclear Co(III) complex. The resulting product contains inorganic phosphate bridging the two metal centers in the diamond core. Results indicate that the dinuclear cobalt complexes may prove to be excellent structural and functional models of the phosphatases studied. Only a partial negative charge on the leaving group oxygen at the transition state was evident from a detailed analysis of the leaving group dependence for the hydrolysis of the dinuclear cobalt complexes.

Research was conducted to examine the electronic structure of substituted Co(II)(acacen) complexes and the Co(II)(salen) complexes by hybrid density functional approaches. Full geometry optimization was used and the optimized geometries were compared to experimental values. Results indicate that a more flexible basis set was needed when using standard effective core potentials for cobalt. Findings also reveal that the inclusion of basis set superposition error and the zero point correction severely reduced the magnitude of the calculated binding energy.

Research was conducted to examine the syntheses, structures and reactivities of isolated (LCo(super III)-OOR) complexes with L = pentadentate strong-field ligands and R = CMe3, CMe2Ph, CMe2CH2Ph, CHMe2, c-C6H11 and CH2CH2CH3(super 4,5). Results demonstrate that the (LCo(super III)-OOR) complexes decompose largely through O-O bond homolysis and yield RO* radicals in the reaction mixtures.

Research was conducted to examine the structural spectroscopic, electrochemical and magnetic properties of cobalt(II)derivative of (ethylsulfanyl)porphyrazine, Co(OESPz), in comparison with those of a peripherally substituted porphyrin, CoOEP, and of a well-studied tetraazapyrrole complex, CoPc. Results based on density functional calculations reveal that the ligand framework strongly influences the energy of the one-electron levels.

Catalytic films were produced through the covalent binding of vitamin B12 poly-L-lysine. The latter compound is covalently bound to graphite electrodes resulting in an ionic polymer coating that is stable in microemulsions. The films have reversible Co(II)/Co(I) voltammetry and were stable in microemulsion for four to five days. They can be used in the dehalogenation of various organohalides in water and microemulsions and for alkylation of activated olefins.

The synthesis and characterization of a cobalt complex containing N-(2-pyridylmethyl)urea, and of six complexes containing phenyl-substituted N-2-pyridylmethyl-N'-(X)phenylureas, where (X = 4-H, 4-CH3, 4-Br, 3-Cl, 4-CF3, and 4-NO2), are presented. The complexes were characterized by UV-vis, FIR, 1H NMR and 13C NMR spectroscopy and by elemental analysis.

The synthesis and characterization of the stoichiometrically related complex, (Co(HCONH2)2(HCO2)2)x, are described. The structure involves cobalt ions which are bridged by formate ions in an extended two-dimensional, square lattice, array. The results of magnetic studies showed that magnetic moment decreases with temperature to 9 K at which point there is an increase to a maximum value before decreasing with decreasing temperature in the lowest temperature region. The compound showed antiferromagnetic behavior at temperatures above 9 K.

The synthesis of the air-stable, free-radical, low-spin Co(III) complex, (Bu(sub 4)N)(sub 2) (3,5-Co(DBSQ)(CN)(sub 4))*1/2 H(sub 2)O*1/4CH(sub 2)Cl(sub 2), where 3,5-DBSQ is the semiquinone anion derived from the one-electron reduction of 3,5-d-tert-butyl-1,2-benzoquinone, is described. The synthetic route involves the reaction of CO(II) tetramer (Co(3,5-DBSQ)(sub 2))(sub 4) with Bu(sub 4)NCN in THF. The resulting Co(III) product is insoluble in THF while the Co(II) product remains in solution.

A study was conducted to analyze the second-sphere interaction for a series of supercomplexes determined from the binding of the photochemical active metal complex, (Co(CN)6)(super 3-), with preorganized protonated polyammonium macrocyclics. Results indicated that the structure distortions in the supercomplexes correlated with the second-sphere interaction resulting from the lowering of site-symmetry at cobalt.

Voltammetry, electrolysis spectroelectrochemistry and electron paramagnetic resonance (EPR) spectroscopy were used to study the oxidations and reduction of 48-electron metal clusters containing a tricobalt core. Specifically, three isomers of Cp3Co3(CO)3 were studied . Results showed that simple cyclic voltammetry responses arise from a rapid equilibration between two isomers rather than from a lack of structural change accompanying charge transfer.The 49 electron anions of the tricobalt complexes showed EPR spectra consistent with antibonding in the trimetallic plane.

Research was conducted to examine the electron-transfer properties of the dinuclear complex (fulvalenediyl)Co2(Et2B4H4)2 using spectroscopic and electrochemical methods. Optical spectroscopy, IR spectroscopy and electron spin resonance spectroscopy were performed in the B-H stretching region. Results suggest strong metal-metal interactions in the d6d7 monoanion which appear to be greater for the electronic configuration with the higher electron count.

The redox condition of the early cobalt (Co) tetrapyrrole intermediates in vitamin B12 biosynthesis was examined to determine the substrate and redox state preference of the first methyl transferase distinct in the anaerobic vitamin B12 pathway, CBiL, derived from the Salmonella typhimurium. It was believed that the requirement for the anaerobic pathway is the incorporation of Co(II) into the tetrapyrrole ligand before ring contraction. It was discovered that CBiL had an absolute prerequisite for the presence of metal ion Co(II), nickel(II) or zinc(II) within the precorrin.

A study is conducted on new triaryltin- and trihalomethylcobalt(III) porphyrin complexes. The compounds were prepared by reacting stannanes R3SnH (R = n-Bu, Ph) with CoIII(OEP)CH3 or CoII(OEP) to form CoIII(OEP)SnR3 and CH4 or H2, respectively. It is shown that the bond dissociation energy of the Co-Sn bond was larger compared to the Co-C bond in alkylcobalt(III) complexes. However, the Co-Sn was cleaved when oxidized by I2 or electrochemical means.

A study is conducted on the encapsulation of a cobalt(II) tris(bipyridyl) complex ion in zeolite-Y supercages. It is shown that the spin-state interconversion phenomenon following encapsulation is intramolecular in origin. The encapsulation of the (Co(bipy)3)2+ ion also forces it to adopt a near-octahedral geometry due to the topology of the supercage forces. An analysis using the angular overlap ligand field model is discussed.

Stopped-flow spectrophotometry was used to investigate the temperature dependence of the kinetics of the carbon-cobalt bond of 5'-deoxyadenosylcobalamin (AdoCbl) catalyzed by the ribonucleotide triphosphate reductase of Lactobacillus leichmannii. The enzyme was found to catalyze the cobalt-carbon bond homolysis of AdoCbl by a factor of 1.6x10 9 at 37 degrees Celsius. It appeared to catalyze the cobalt-carbon bond cleavage reaction entirely enthalpically.

Vitamin B12 was examined through a single-crystal cobalt nuclear magnetic resonance (NMR) study at 11.75 T. Findings showed that the cobalt nucleus in the vitamin experiences a highly anisotropic chemical shift spanning 1200 ppm about the isotropic chemical shift of 4549 ppm. The two tensors describing the orientation dependence of these NMR interactions showed distinct orientations with respect to the vitamin. The study demonstrated the importance and feasibility of single-crystal NMR to provide this orientation information in metal-centered biological assemblies.