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Mixed-Ligand Cobalt(III) Complexes of a Naturally Occurring Coumarin and Phenanthroline Bases as Mitochondria-Targeted Dual-Purpose Photochemotherapeutics
The bioessential nature of cobalt and the rich photochemistry of its coordination complexes can be exploited to develop potential next-generation photochemotherapeutics. A series of six novel mixed-ligand cobalt(III) complexes of the formulation [Co(B)2(L)]ClO4 (1-6), where B is an N,N-donor phenanthroline base, namely, 1,10-phenanthroline (phen in 1 and 4), dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq in 2 and 5), and dipyrido[3,2-a:2′,3′-c]phenazine (dppz in 3 and 6), and L is an O,O-donor dianionic ligand derived from catechol (1,2-dihydroxybenzene, cat2-, in 1-3) or esculetin (6,7-dihydoxycoumarin, esc2-, in 4-6), have been prepared and characterized, and their light-triggered cytotoxicity has been studied in cancer cells. The single-crystal X-ray diffraction structures of complexes 1 (as PF6- salt, 1a) and 2 show distorted octahedral geometries around the cobalt(III) center formed by the set of N4O2 donor atoms. The low-spin and 1:1 electrolytic complexes 1-6 display a d-d transition around 700 nm. Complexes 4-6 with a coordinated esc2- ligand additionally display a π→ π? intraligand transition centered at 403 nm. Complexes 4-6 possessing a naturally occurring and photoactive esc2- ligand show high visible-light-triggered cytotoxicity against HeLa and MCF-7 cancer cells, yielding remarkably low micromolar IC50 values while being much less toxic under dark conditions. Control complexes 1-3 possessing the photoinactive cat2- ligand show significantly less cytotoxicity either in the presence of light or in the dark. The complex-induced cell death is apoptotic in nature caused by the formation of reactive oxygen species via a type 1 photoredox pathway. Fluorescence microscopy of HeLa cells treated with complex 6 reveals mitochondrial localization of the complex. A significant decrease in the dark toxicity of free esculetin and dppz base is observed upon coordination to cobalt(III). Complexes bind to calf-thymus DNA with significant affinity, but 6 binds with the greatest affinity. Complex 6 efficiently photocleaves supercoiled DNA to its nicked circular form when irradiated with visible light via a photoredox type 1 pathway involving hydroxyl radicals (HO?). Thus, complex 6 showing remarkable visible-light-triggered cytotoxicity but negligible toxicity in the dark is a good candidate for cancer photochemotherapy applications.
Hussain, Akhtar,Kumar, Arun,Sahoo, Somarupa,Sarkar, Tukki
supporting information
p. 6649 - 6662
(2021/05/06)

Synthesis, molecular, and crystal structures of 3d transition metal cyanocyclopentadienides [M(MeOH)n(H2O)4-n{C5(CN)4X}2] (M=Mn, Fe, Co, Ni, Cu, Zn; X=H, CN, NH2, NO
The reaction of the 3d transition metal dichlorides MCl2 (M=Mn, Fe, Co, Ni, Cu, Zn) with the silver salts of substituted tetracyanocyclopentadienides Ag+ [C5(CN)4X]- (X=CN, H, NH2 NO2
Sünkel, Karlheinz,Reimann, Dietmar,Nimax, Patrick
p. 109 - 118
(2018/12/11)

Cobalt Oxide Materials for Oxygen Evolution Catalysis via Single-Source Precursor Chemistry
The utilization of metal alkoxides as single-source precursors for (mixed-)oxide materials offers remarkable benefits, such as the possibility to precisely control the metal ratio in the resulting material, highly homogeneous distribution of the elements in the film, and the low temperatures required for film processing. Herein we report on the isolation and characterization of the bimetallic Co-Mo alkoxide [Co3Mo4O10(OCH3)10(dmf)4] (Co3Mo4; dmf=N,N-dimethylformamide), which was prepared by the anion metathesis reaction of the corresponding metal chlorides. The Co-Mo alkoxide was explored as a well-defined precursor of cobalt oxide catalysts for the oxygen evolution reaction (OER) in alkaline electrolyte MOH. The catalysts demonstrated excellent activity in the OER, manifested in low onset potentials and Tafel slopes and superb stability under the operating conditions both in alkaline and nearly neutral media. It was observed that the nature of the metal cation of the alkaline electrolyte MOH (M+=Li+, Na+, K+, Cs+) greatly affected the catalytic performance of the material. We propose that the positive effect of larger metal cations on the film activity in the OER could be explained by the higher hydration enthalpies of larger ions and enhanced mass transport within a larger interlayer space between the [CoO2]δ?∞ sheets of the in situ formed binary oxides. It may be deduced that this trend is universal and may be extended to other types of metal oxides forming layered structures during the OER.
Kuznetsov, Denis A.,Konev, Dmitry V.,Sokolov, Sergey A.,Fedyanin, Ivan V.
p. 13890 - 13896
(2018/09/14)

Bis(dinitrogen)cobalt(-1) Complexes with NHC Ligation: Synthesis, Characterization, and Their Dinitrogen Functionalization Reactions Affording Side-on Bound Diazene Complexes
Late-transition-metal-based catalysts are widely used in N2 fixation reactions, but the reactivity of late-transition-metal N2 complexes, besides iron N2 complexes, has remained poorly understood as their N2 complexes were thought to be labile and hard to functionalize. By employing a monodentate N-heterocyclic carbene (NHC), 1,3-dicyclohexylimidazol-2-ylidene (ICy) as ligand, the cobalt(0)- and cobalt(-1)-N2 complexes, [(ICy)3Co(N2)] (1) and [(ICy)2Co(N2)2M]n (M = K, 2a; Rb, 2b; Cs, 2c), respectively, were synthesized from the stepwise reduction of (ICy)3CoCl by the corresponding alkaline metals under a N2 atmosphere. Complexes 2a-c in their solid states adopt polymeric structures. The N-N distances (1.145(6)-1.162(5) ?) and small N-N infrared stretchings (ca. 1800 and 1900 cm-1) suggest the strong N2 activation of the end-on N2 ligands in 2a-c. One electron oxidation of 1 by [Cp2Fe][BF4] gave the cobalt(I) complex devoid of N2 ligand [(ICy)3Co][BF4] (3). The bis(dinitrogen)cobalt(-1) complexes 2a-c undergo protonation reaction with triflic acid to give N2H4 in 24-30% yields (relative to cobalt). Complexes 2a-c could also react with silyl halides to afford diazene complexes [(ICy)2Co(η2-R3SiNNSiR3)] (R = Me, 6a; Et, 6b) that are the first diazene complexes of late transition metals prepared from N2 functionalization. Characterization data, in combination with calculation results, suggest the electronic structures of the diazene complexes as low-spin cobalt(II) complexes containing dianionic ligand [η2-R3SiNNSiR3]2-. Complexes 1, 2a-c, 6a, 6b, and (ICy)2CoCl2 proved to be effective catalysts for the reductive silylation of N2 to afford N(SiMe3)3. These NHC-cobalt catalysts display comparable turnover numbers (ca. 120) that exceed the reported 3d metal catalysts. The fine performance of the NHC-cobalt complexes in the stoichiometric and catalytic N2-functionalization reactions points out the utility of low-valent low-coordinate group 9 metal species for N2 fixation.
Gao, Yafei,Li, Guangyu,Deng, Liang
p. 2239 - 2250
(2018/02/19)

Enantioselective precipitate of amines, amino alcohols, and amino acids via schiff base reaction in the presence of chiral ionic liquid
Two novel chiral ionic liquids are synthesized as the chiral selector. Racemates of amines, amino alcohols, and amino acids could generate enantioselective precipitate with multicomponent self-assemblies under mild conditions. The approach allows for enan
Wu, Datong,Cai, Pengfei,Zhao, Xiaoyong,Pan, Yuanjiang
p. 5018 - 5021
(2017/11/06)

Synthesis and Characterization of 2-Pyridinylmethylene-2-quinolyl Hydrazone Cobalt(III) Complexes. Reactivity Trends and Solvent Effect on the Initial and Transition States of Base Catalyzed Hydrolysis
The complexes of pyridine-2-aldehyde-2-quinolylhydrazone Co(III) nitrate [Co(paqh)2](NO3)2, methyl-2-pyridylketone-2-quinolinhyrazone Co(III) nitrate [Co(mpkqh)2](NO3)2, and phenyl-2-pyridylketon-2-quinolinhyrazone Co(III) nitrate [Co(ppkqh)2](NO3)2 were prepared and characterized. Solubilities of Co(III)–hydrazone complexes were measured. Transfer chemical potentials were calculated from the measured solubilities of the Co(III) complexes in aqueous methanol mixtures at 25?°C. The reactivity trends in the transfer chemical potentials are discussed in terms of the nature of the bonded ligands. Kinetics of the base hydrolysis of Co(III)–hydrazone complexes in the aqueous methanol mixtures have been studied at 25?°C, and follow the rate law kobs?=?k2[OH?]. The solvent effects on the reactivity trends of Co(III) complexes are analyzed into initial state (is) and transition states (ts) components. The reaction rates are reduced by the increase of methanol content. The destabilization of the transition state is remarkable compared to the initial state in the aqueous methanol mixtures. The initial state is more hydrophobic in nature than the transition state for Co(III) complex reactions.
Mohamad, Ahmad Desoky M.
p. 1575 - 1595
(2017/09/06)

N-Atom transfer: Via thermal or photolytic activation of a Co-azido complex with a PNP pincer ligand
Thermal or photolytic activation of well-defined mononuclear [Co(N3)(PNP)] (PNP = 2,2′-bis(diisopropylphosphino)-4,4′-ditolylamido) results in the structurally characterized dinuclear species [Co(μ-N;κ3-P,N,N-PNPN)]2 (3), with two N-bridging phosphiniminato bridgeheads. Density Functional Theory (DFT) calculations indicate the intermediacy of a mononuclear cobalt-nitrido complex, followed by N-migratory insertion into a Co-P bond. Reaction of 3 with two equiv. HCl leads to rupture of the dimer with formation of mononuclear [CoCl(PNPNH)] (4) by protonation of the N-bridges.
Vreeken,Baij,De Bruin,Siegler,Van Der Vlugt
supporting information
p. 7145 - 7149
(2017/07/10)

New complexes of 4-[(4-fluorophenyl)amino]-4-oxobut-2-enoic acid with selected transition metal ions: Synthesis, thermal, and magnetic properties
Complexes of 4-[(4-fluorophenyl)amino]-4-oxobut-2-enoic acid, HL, with Mn(II), Co(II), Ni(II), Cu(II), Nd(III), Gd(III), and Er(III) were synthesized and characterized by various physico-chemical methods: elemental analysis, FT-IR, TG, DTG, DSC, TG/FT-IR, XRF, XRD, and magnetic measurements using the Gouy’s method and a SQUID-VSM magnetometer. The complexes were found to be hydrates (except Er(III) complex) containing 1 to 4 molecules of water. The carboxylate groups acted as bidentate ligands.
Ferenc,Sadowski,Tarasiuk,Cristóv?o,Osypiuk,Sarzyński
p. 2719 - 2727
(2017/12/26)

Synthesis and molecular structure of cobalt(II) complex with 1-(1-silatranylmethyl)-1,2,4-triazole
Reaction of cobalt chloride with 1-(1-silatranylmethyl)-1,2,4-triazole in benzene afforded complex CoCl2·2L (L = 1-(1-silatranylmethyl)- 1,2,4-triazole). It was isolated as the solvate [CoCl2·2L] ·CH2Cl2 (1) by recrystallization from dichloromethane and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P21/m with a = 6.798(2) E, b = 20.326(5) E, c = 11.005(3) E, and Z = 4. The cobalt atom is in slightly distorted square-planar environment, coordinated to two nitrogen atoms from two ligands and two chloride ions.
Vasiliev,Zel'Bst,Soldatenko,Bolgova,Trofimova,Voronkov
p. 1001 - 1005
(2013/08/23)

Microwave-assisted carbohydrohalogenation of first-row transition-metal oxides (M = V, Cr, Mn, Fe, Co, Ni, Cu) with the formation of element halides
The anhydrous forms of first-row transition-metal chlorides and bromides ranging from vanadium to copper were synthesized in a one-step reaction using the relatively inexpensive element oxides, carbon sources, and halogen halides as starting materials. The reactions were carried out in a microwave oven to give quantitative yields within short reaction times.
Berger, Matthias,Neumeyer, Felix,Auner, Norbert
supporting information
p. 11691 - 11693
(2013/11/19)

Benzyl alcohol-based synthesis of oxide nanoparticles: The perspective of SN1 reaction mechanism
In this paper, we describe a class of benzyl alcohol-based reactions for the synthesis of a series of inorganic oxide nanoparticles. Benzyl alcohol served as both the solvent and the reagent to interact with various metal chlorides for the synthesis of a series of metal oxides and compound oxides. Typical metal(iv) oxides, like TiO2, metal(iii) oxides, like Fe 2O3, and metal(ii) oxides, like ZnO, with uniform size and special dispersibility, have been prepared through these reactions. The reaction can be illustrated from the perspective of SN1 reaction mechanism attributed to the easier formation of benzyl carbocation and unique reactivity of benzyloxy group with nucleophilic agents. By adjusting the experimental conditions, it was found that this type of reaction is available for the synthesis of many inorganic oxides. The Royal Society of Chemistry 2013.
Hu, Mingjun,Xu, Jiaju,Gao, Jiefeng,Yang, Shiliu,Wong, Julia Shuk Ping,Li, Robert K. Y.
p. 9777 - 9784
(2013/08/23)

Mechanism of reaction between Cobalt(II) oxide and ammonium chloride
A reaction between cobalt oxide and ammonium chloride was studied. A possible mechanism of this reaction was determined by TGA and DSC. The reaction products were identified by IR spectroscopy, chemical and XRD analyses. A multistage mechanism was established for reaction between cobalt oxide and ammonium chloride. Cobalt chloride was determined to be the final product; the reaction occurs via the for-mation and decomposition of (NH4) 3CoCl5, (NH4)2CoCl4, and NH4CoCl3. Pleiades Publishing, Ltd., 2012.
Borisov,D'yachenko,Kraidenko
p. 923 - 926
(2012/10/08)

Synthesis of nanosize Co-Rh systems and study of their properties
Precursor compounds [Co(NH3)6][Rh(NO 2)6] and [Co(NH3)6][Co(NO 2)6], solid solutions [Co(NH3)6] [Rh(NO2)6]1-x [Co(NO2)6] x, and solid solutions Na3[Rh1-x Co x (NO2)6] were synthesized and studied by IRspectroscopy and elemental, X-ray phase, X-ray diffraction, and thermog ravimetric analyses. X-ray phase analysis was employed to examine products of thermal decomposition of precursors in the atmospheres of hydrogenand helium. Catalysts with a Co-Rh active system, supported by ZrO 2, were prepared and tested in the reaction of steam conversion ofethanol.
Gubanov, A. I.,Churakova, E. M.,Badmaev, S. D.,Sytnikov, P. V.,Filatov, E. Yu.,et al.
p. 1677 - 1683
(2012/03/09)

Molecular complexes of cobalt(II) and Zinc(II) chlorides and bromides with 1-piperidinyl dimethylcarbamodithioate (L): Crystal structures of L and [ZnLBr2]
Complexes of MX2(M = Co, Zn; X = Cl, Br) with 1-piperidinyl dimethylcarbamodithioate (L) of composition [MLX2] have been synthesized. The compounds have been studied by elemental analysis; X-ray diffraction; thermogravimetry; conductometry; magnetochemistry; and IR, 1H NMR, and electronic absorption spectroscopy. The ligand molecule is coordinated to the metal atoms in a bidentate chelating mode through the thione sulfur atom and the sulfenamide nitrogen atom to form a five-membered chelate ring. The structures of L and [ZnLBr2] have been determined by X-ray crystallography.
Seifullina,Khitrich,Vologzhanina
p. 184 - 189
(2011/05/04)

Field-induced reversible magnetocaloric effect in CoCl2
A sign change of the magnetocaloric effect is induced by a magnetic field, which is related to a field-induced transition from the antiferromagnetic to the ferromagnetic state below the Néel temperature of CoCl2 nanoparticles. The reversible magnetic-entropy change -ΔSm (4.1 and 11.5 J kg-1 K-1 at 27 K for a field change of 3 and 7 T, respectively) almost without hysteresis and the large cooling power (83.4 and 148 J kg-1, correspondingly) indicates that CoCl2 is a potential candidate for application in magnetic refrigeration in the low-temperature range.
Liu,Liu,Guo,Gong,Lv,Zhang
p. 26 - 28
(2011/01/08)

Reactions of 2-chlorobutane with polynuclear bimetallic aluminum and cobalt chloride complexes: Low-temperature synthesis and structure of adducts
Co-condensation of aluminum and cobalt chlorides and 2-chlorobutane leads to the formation of triple complexes. Density functional method PBE was used for the quantum chemical calculations of structures and harmonic vibration frequencies. The structures of associates were established by the comparison of experimental and theoretical IR spectra. Introduction of cobalt chloride into the system 2-chlorobutane-aluminum chloride leads to the formation of a triple molecular associate, in which coordination of the organic substrate with the bimetallic complex is accomplished through the transition metal atom. The triple complex is stable in the temperature range 80-240 K and in contrast to the binary complex of butyl chloride with aluminum halide is not capable of self-ionization to form sec-butyl cation.
Shilina,Smirnov,Bakharev
p. 1119 - 1125
(2011/02/17)

Interaction between samarium and cobalt carbonates in aqueous medium
The Sm2(CO3)3-CoCO3-H 2O system was studied using isothermal crystallization (295 K). The compounds Sm2(CO3)3 ? 8H2O, Sm2Co5(CO3
Burlakova,Shilkin
p. 23 - 26
(2010/04/25)

A group of new selenite-chlorides of strontium and d-metals (Co,Ni): Synthesis, thermal behavior and crystal chemistry
The new selenite-chlorides with composition Sr3(SeO3)2Cl2 (I) and Sr2M(SeO3)2Cl2 (M=Co, Ni (II and III)) were obtained. They crystallize in monoclinic system I: space
Berdonosov, Peter S.,Olenev, Andrey V.,Kuznetsov, Alexei N.,Dolgikh, Valery A.
p. 77 - 82
(2009/04/14)

Electrodeposition of RE-TM (RE = La, Sm, Gd; TM = Fe, Co, Ni) films and magnetic properties in urea melt
Rare earth (RE)-3d transition metal (TM) films were codeposited in low temperature urea-acetamide-NaBr-KBr-RECl3-TMCl2 baths by potentiostatic electrolysis. Cyclic voltammetry is used to investigate the electrochemical behavior of RE
Li, Jiaxin,Lai, Heng,Fan, Biqiang,Zhuang, Bin,Guan, Lunhui,Huang, Zhigao
p. 547 - 551
(2009/10/30)

Syntheses, crystal structures and magnetic properties of three novel cobalt(ii) complexes containing imidazole derivative groups
Three Co(ii) complexes with the formulas: {[Co2(Bib) 3Cl2]Cl(CH3COO)}·CH 3OH·H2O (1), [Co2(Bib) 3Cl2]Cl2·(CH3OH) 2·H2
Yang, Hong,Chen, Jia-Min,Sun, Jing-Jia,Yang, Shi-Ping,Yu, Jie,Tan, Hong,Li, Wei
p. 2540 - 2551
(2009/12/23)

Thermodynamics and phase equilibrium studies of silver halide-cobalt(II) halide systems
Phase diagrams for the systems AgCl-CoCl2and AgBr-CoBr 2were determined by differential scanning calorimetry. The systems are of the eutectic type. Eutectic points are at 271±2 K, 19.5 mol% CoCl2and 653±2 K, 17.0 mol% CoBr
Krzy?ak,Wojakowska, Alina
p. 721 - 726
(2009/02/06)

Aluminum halide-cobalt halide polynuclear complexes active in low-temperature conversion of alkanes: Formation, molecular structures, and IR spectra
Low-temperature FT-IR studies of products of co-condensation of aluminum chloride and cobalt chloride in hydrocarbon matrices were carried out in the temperature range 80-250 K. DFT quantum mechanical calculations of the geometry and vibrational frequenci
Shilina,Bakharev,Smirnov
p. 2251 - 2260
(2010/02/16)

Synthesis and thermal analysis of tetraethylammonium bromochlorocobaltates(II) [Et4N]2[CoBrnCl4-n]
New mixed-ligand tetraethylammonium halogenocobaltates(II) of general formula [Et4N]2[CoBrnCl4-n] have been synthesized. Their thermal properties were characterized on the basis of the TG and DTG curves taken in
Styczeń, Emilia,Warnke, Zygmunt,Wyrzykowski, Dariusz
p. 84 - 89
(2008/10/09)

Melting and high-temperature solid state transitions in cobalt(II) halides
Melting and high temperature solid-state transitions in CoCl2 and CoBr2 are widely discussed. On the basis of DSC and conductometric measurements it was found that melting process of CoCl 2 is preceded by a solid-state transition appearing about 20 K below the melting point of CoCl2. Due to deconvolution of the thermograms, the enthalpy of fusion and that of solid-state transition were found to be 36.4 and 9.6 kJ mol-1, respectively. Melting points of CoCl2 and CoBr2 were established to be 999.0 and 949.7 K, respectively. Hitherto unknown enthalpy of fusion of CoBr2 was determined to be 27.2 kJ mol-1. A solid-state transition in CoBr2 at 650 K has been confirmed. Springer-Verlag 2007.
Wojakowska, Alina,Krzy?ak,Plińska, Stanis?awa
p. 525 - 530
(2008/10/09)

Preparation of α-MnO2 nanorods and Co3O 4 submicrooctahedrons by molten salt route
α-MnO2 nanorods and Co3O4 submicroctahedrons have been obtained by simple molten salt preparation route using cheap reagents. Particle size and morphology of the powders were studied by transmission electron microscopy (TE
Ran, Songlin,Gao, Lian
p. 688 - 689
(2008/02/07)

Synthesis, spectroscopic and magnetic properties of nonaalkoxodistannatocobalt(II) derivatives
Nonaalkoxodistannate complexes of cobalt(II) of the types [Co(η4-Sn2(OR)9(μ-Cl)]2(R = Pri(1), Et (2)) and [Co{η3-Sn2(OR) 9}2] (R = Pri(3), Et(4)) have been prepared by the interactions of anhydrous CoCl2 with NaSn2(OR) 9(R = Pri, Et) in 1:1 and 1:2 molar ratios, respectively (where η3 and η4 represent the tri- and tetradentate ligation of {Sn2(OR)9}-, respectively). The dimeric chloro(nonaalkoxodistannato)cobalt(II) complexes [Co {η4-Sn2(OR)9 J (μ-Cl)]2, (1) and (2) have been found to be useful precursors for the synthesis of a variety of interesting heterobimetallic derivatives such as [Co {η4- Sn2(OPri)9} (μ-OPri)]2 (5), [Co[η4-Sn2(OEt)9}(μ-OEt)] 2 (6), [Co{η4-Sn2(OPri) 9}(μ-OCH2CH2NH-CH3)]2 (7), [Co{η4-Sn2(OEt)9}(μ-OCH 2CH2-NHCH3)]2 (8), [Co{η4-Sn2(OPri)9} (μ-OCH2CH2-OCH3)]2 (9), [Co(η4-Sn2(OEt)9}(μ-OCH 2CH2OCH3)]2 (10), [Co(η4-Sn2(OPri)9} (μ-OCH2CH2OC2H5)]2 (11), and [Co(η4-Sn2(OEt)9)(μ-OCH 2CH2OC2H5)]2 (12). All these complexes (1)-(12) are highly moisture-sensitive, coloured solids, soluble in organic solvents. Molecular weights determined cryoscopically in benzene solutions show dimeric nature for (1),(2),(5)-(12) and monomeric behaviour for (3) and (4). These complexes have been characterized by elemental analyses, spectroscopic (UV-vis, IR) and magnetic measurements.
Agrawal, Neetu,Singh, Anirudh
p. 772 - 777
(2008/02/09)

Reactions of cobalt oxide with chlorine
We report the thermodynamic calculations and experimental studies of the kinetics of the reaction of Co3O4 with chlorine at 300-850°C. The show that cobalt chloride sublimation is controlled by the rate of chloride evolution from the
Anufrieva,Derlyukova
p. 1840 - 1843
(2008/10/09)

Synthesis, structure and physical properties of trinuclear M3tdt3(PEt3)3 (M = FeII, CoII) clusters containing metal-metal bonds
Trinuclear M3tdt3(PEt3)3 (M = FeII for I, CoII for II) clusters have been synthesized from the reaction between M(PEt3)2Cl2 and Na2tdt (tdt = toluene-3,4-dithiolate) in MeCN. Both complexes have been characterized by elemental analyses, FT-IR, UV-Vis, FAB-MS, 1H NMR and cyclic voltammetry. Structures of Fe3tdt3(PEt3)3 (I) and Co3tdt3(PEt3)3 (II) were determined by single crystal X-ray crystallography. The Fe3 triangular core of the 48-electron complex I, with an isosceles triangular geometry, showed very short Fe-Fe distances of 2.4014(13) and 2.4750(12) ?, which are comparable to the extensive M-M frameworks found in the FeMo-cofactor in nitrogenase. The isostructural Co3tdt3(PEt3)3 (II), with an analogous Co3 coordination geometry, showed short Co-Co distances of 2.4442(9) and 2.5551(10) ?. The slightly longer M-M distances in complex II were explained by a total valence electron counting argument. Cyclic voltammetry of Fe3tdt3(PEt3)3 (I) showed robust reduction waves compared to Co3tdt3(PEt3)3 (II). Temperature-dependent effective magnetic moment measurements of I and II showed both clusters behave similarly and the magnetic property of the M3 equilateral triangle core with extensive metal-metal interactions was characterized as degenerate frustration.
Kim, Mihyang,Han, Jaehong
p. 2949 - 2956
(2008/10/09)

Mononuclear metal complexes of organic carboxylic acid derivatives: Synthesis, spectroscopic characterization, thermal investigation and antimicrobial activity
Two Schiff base ligands bearing organic acid moiety, vis., N-(2-thienylmethylidene)-2-amino-4-chlorobenzoic acid (HL1) and N-(2-hydroxybenzylidene)-2-amino-4-chlorobenzoic acid (H2L2) have been synthesized by the interaction of 2-thiophenecarboxaldehyde and 2-hydroxybenzaldehyde with 2-amino-4-chlorobenzoic acid. Co(II), Ni(II), Cu(II) and Zn(II) complexes of these ligands have been prepared. They are characterized on the basis of analytical data, molar conductance, IR, 1H NMR, UV-vis, mass spectra, magnetic measurements, thermal analysis and X-ray powder diffraction technique. The molar conductance data reveal that these complexes are non-electrolytes. The ligands are coordinated to the metal ions in a terdentate manner with ONO/ONS donor sites of the carbonyl oxygen, azomethine nitrogen and phenolic oxygen or thiophenic sulphur. An octahedral structure is proposed for the prepared metal complexes and some ligand field parameters (Dq, B and β) in addition to CFSE were calculated. The thermal stability of the metal complexes is evaluated. The Schiff base ligands and their metal complexes have been tested against four species of bacteria as well as four species of fungi and the results have been compared with some known antibiotics.
Abd El-Wahab, Zeinab H.
p. 25 - 38
(2008/02/03)

A vapor-solid strategy to silica sheathed metal nanostructures and microstructures via reactions of metal chlorides with silicon
A facile vapor-solid strategy has been developed to prepare silica-sheathed metal micro/nanostructures with controllable shapes. As examples, silica-sheathed nickel nanowires (diameter ～50 nm), microcubes (edge length 1-3 μm), nanocubes (edge length ～200 nm) with an epitaxial tail (diameter 2 structures are discussed. The method is expected to be applied to a wider range of metals.
Wang, Jin,Zhang, Haoxu,Ge, Jianping,Li, Yadong
p. 807 - 811
(2008/10/09)

Synthesis and characterization of [Co(NH3)5NO 2][M(NO2)4] (M = Pt, Pd) compounds and their thermolysis products
Compounds [Co(NH3)5NO2][Pd(NO 2)4] (I) and [Co(NH3)5NO 2][Pt(NO2)4] ? 1.5H2O (II) have been crystallized from solution. Their crystal
Yusenko,Shubin,Skryabina,Baidina,Korenev
p. 521 - 530
(2008/10/09)

Studies on transition metal murexide complexes
Iron cobalt nickel copper zinc cadmium and mercury murexide complexes have been prepared and characterized. The thermal properties of these complexes are studied deeply by DTA technique where their thermal peaks are explained. The multi-stages thermal dec
Masoud,Kassem,Shaker,Ali
p. 549 - 555
(2008/10/09)

Catalytic electroreduction of oxygen on products of pyrolysis of heterobimetallic complexes of zinc
Electrocatalysts for reduction of oxygen were synthesized from AG-3 activated carbon promoted with pyrolized heterobimetallic complexes [CoLCl 2] [ZnDMFACl3] and [ML][ZnCl4] (M = Cu 2+, Ni2+; L = 4,6,
Pirskii,Kublanovskii,Shevchenko,Kokozei
p. 1964 - 1968
(2008/02/08)

On the chemical vapor transport of ternary transition metal- and earth
The chemical vapor transport of transition metal tungstates MWO4 (M=Mn, Co, Ni, Cu, Zn, Cd) was investigated in dependence on mean transport temperature (923 K to 1223 K) and amount of transport agent Cl2. All tungstates migrate in a temperature gradient ΕT = 100 K from the region of higher temperature to the lower temperature with migration rates of 0.5 to 8 mg/h depending on experimental conditions. The transport behaviour was determined by continuous measurement of mass change during the transport experiments. The results were compared to thermo chemical calculations and the influence of moisture content discussed in detail. MgWO4 migrates under the influence of Cl2 in a temperature gradient 1273 K to 1173 K (migration rate 0.7 mg/h), CaWO4 and SrWO4 in a temperature gradient 1423 K to 1323 K (migration rate 0.1 mg/h).
Steiner, Udo
p. 1706 - 1714
(2008/10/09)

Thermal decomposition studies on cobalt(II) complexes of 4-N-(4′-antipyrylmethylidene)aminoantipyrine with varying counter ions
The phenomenological, kinetic and mechanistic aspects of the nitrate, chloride, bromide and iodide complexes of cobalt(II) with 4-N-(4′- antipyrylmethylidene)aminoantipyrine (AA) have been studied by TG and DTG techniques. The kinetic parameters such as a
Madhu,Radhakrishnan,Williams, Edna,Linert
p. 157 - 161
(2008/10/09)

A thermal decomposition study on cobalt(II) complexes of 1,2-bis(imino-4′-Antipyrinyl)ethane
The phenomenological, kinetic and mechanistic aspects of thermal decomposition of perchlorate, nitrate, chloride, bromide and iodide complexes of cobalt(II) with the Schiff base 1,2-bis(imino-4′ antipyrinyl)ethane (GA) have been studied by TG and DTG analyses. The kinetic parameters like the activation energy, pre-exponential factor and entropy of activation were calculated. The decomposition reactions follow 'random nucleation with one nucleus on each particle - Mampel model'.
Madhu,Radhakrishnan,Grunert,Weinberger,Linert
p. 813 - 821
(2008/10/09)

Cryosynthesis, structure, and spectroscopic properties of aluminum chloride-cobalt(II) chloride complexes: Experiment and calculations
Products of co-condensation of aluminum chloride and cobalt(II) chloride vapors were studied by low-temperature (80-200 K) IR spectroscopy. In addition to 2:1 complexes, previously unknown equimolar associates were found and their IR spectra were investigated. Quantum-mechanical calculations were carried out including electron correlation with the use of the B3LYP and PBE density functionals. The geometric structures were optimized and harmonic vibrational frequencies of the molecules of aluminum chloride, cobalt chloride, and their complexes with different compositions were calculated. Under conditions of limited molecular mobility, the (AlCl3)2·CoCl 2 complexes can be stabilized in structures containing the Co atom in a tetrahedral or distorted octahedral environment. Their thermal stability limits were determined. It was found that labile ionic species are generated in the reactions of aluminum chloride complexes with cobalt chloride with different compositions at 120-170 K.
Shilina,Bakharev,Kuramshina,Smirnov
p. 297 - 305
(2007/10/03)

Preparation of nickel, iron, and cobalt nanopowders via reduction of salts with sodium dissolved in liquid ammonia
Nickel, iron, and cobalt powders are prepared via reduction of salts with sodium dissolved in liquid ammonia. The low temperature of the process and the ability of liquid ammonia to stabilize dangling chemical bonds notably reduce the growth rate of metal
Novikov,Pan'kov,Kunitskii
p. 809 - 814
(2008/10/09)

A thermal decomposition study on cobalt(II) complexes of 1,2-di(imino-4′-antipyrinyl)ethane
The phenomenological, kinetic and mechanistic aspects of thermal decomposition of perchlorate, nitrate, chloride, bromide and iodide complexes of cobalt(II) with the Schiff base 1,2-di(imino-4′-antipyrinyl)ethane (GA) have been studied by TG and DTG analyses. The kinetic parameters like the activation energy, pre-exponential factor and entropy of activation were calculated. The decomposition reactions follow random nucleation with one nucleus on each particle - Mampel model .
Madhu,Radhakrishnan,Grunert, Matthias,Weinberger, Peter,Linert, Wolfgang
p. 29 - 36
(2008/10/08)

Thermochemistry of the complexes of some microelements and histidine
Solid complexes of M(His)2Cl2·nH2O (M=Mn, Co, Ni, Cu) of MnCl2·6H2O, CoCl 2·6H2O, NiCl2·6H2O, CuCl2·2H2O and L-α-histidine (His) have been prepared in 95% ethanol solution and characterized by elemental analyses, chemical analyses, IR and TG-DTG. The constant-volume combustion energies of the complexes have been determined by a rotating-bomb calorimeter. The standard enthalpies of formation of the complexes have been calculated as well.
Chen,Gao,Yang,Hu,Shi
p. 967 - 975
(2008/10/08)

Formation and magnetic characteristics of cobalt-carbon nanocluster magnets embedded in amorphous carbon matrices
Co-C2 nanocluster magnets are formed in amorphous carbon by high pressure reaction of Co4(CO)12 and CH2Cl2. The average size of the clusters is 12 nm. Structural characteristics are investigated by tr
Nishi, Nobuyuki,Kosugi, Kentaroh,Hino, Kazuyuki,Yokoyama, Toshihiko,Okunishi, Eiji
p. 198 - 203
(2008/10/08)

Synthesis, characterization and thermal behavior of cobalt(II) 5-chloro-piridylamides complexes
Purple cobalt(II) complexes containing 5-chloro-2-aminepyridylacetamide (CPA), 5-chloro-2-aminepyridylpropionamide (CPP) and 5-chloro-2-aminepyridylbutyramide (CPB) ligands were prepared from ethanolic solutions. The general stoichiometry CoL2Cl2 (L = ligand) was determined from elemental analysis data. Infrared results show monodentate CPA and CPP ligands through the aromatic nitrogen atom, CPB is bidentate through the aromatic nitrogen atom and carboxyl group. Thermogravimetric curves under nitrogen showed in the final stage all complexes presented a mixture of cobalt(II) chloride and metallic cobalt as residue. The complexes containing CPA and CPP ligands decomposed in various stages with integral loss of ligand or partial loss of the chloride. Only two steps of decomposition are seen for CPB compound.
Lima, Cicero B.A.,Espínola, José G.P.,De Oliveira, Severino F.,Arakaki, Luiza N.H.,Fonseca, Maria G.,Airoldi, Claudio
p. 117 - 120
(2008/10/08)

Compression behavior of the delafossite-type metallic oxide PdCoO 2 below 10 GPa
The compression behavior of delafossite-type metallic oxide PdCoO 2 below 10 GPa has been investigated by in situ high pressure X-ray diffraction measurement using synchrotron radiation. It is found that the delafossite-type structure of PdCoO2 is stable below 10 GPa. It should be noted that compression behavior of PdCoO2 is anisotropic. Pressure dependence of the lattice parameters indicates that the a-axis is more compressible than the c-axis. The lattice parameter ratio c/a in the hexagonal unit increases with increasing pressure. The calculated zero-pressure bulk modulus is 224 GPa. It is found that the above characteristic compression behaviors of PdCoO2 are the same as those of the delafossite CuFeO2. The compressibilities of the a-axis of both PdCoO 2 and CuFeO2 are highly different although those of the c-axis are almost the same.
Hasegawa,Tanaka,Yagi,Takei,Inoue
p. 303 - 307
(2008/10/08)

Synthesis of cobalt(II) and iron(II) complexes with the ligand bis(2-diphenylphosphinoethyl)methylamine and their catalytic action on ethylene oligomerization. X-ray crystal structure of
Complexes [MCl2{CH3N(CH2CH2PPh2)2}] (1, M = Co; 2, Fe) were prepared by a modified procedure. The X-ray structural determination of 1 reveals that the cobalt(II) complex is four-coordinate with a distorted tetrahedral coordination geometry. The tertiary amine CH3N(CH2CH2PPh2)2 acts as a bidentate ligand through two phosphorus atoms. The Co-P distances of 2.3666(14) and 2.3731(15) ? found in 1 are significantly longer than general Co-P bond lengths. The incoordinate N atom of the ligand locates at the apical position trans to one of the chlorides. The catalytic properties of 1 and 2 in combination with ethylaluminoxane (EAO) as cocatalyst for ethylene oligomerization were studied. The activities of 89.4 kg oligomers mol-1 Co h-1 for 1 and 81.2 kg oligomers mol -1 Fe h -1 for 2 (100 equivalents of EAO, 180 °C and 1.8 MPa ethylene) were observed with high selectivity to linear C4-10 olefins.
Wang, Mei,Yu, Xiaomin,Shi, Zhan,Qian, Mingxing,Jin, Kun,Chen, Jiesheng,He, Ren
p. 127 - 133
(2007/10/03)

Dichlorobis(1-propylimidazolidine-2-thione-κS)cobalt(II)
Cobalt(II) complex, dichlorobis(1-propylimidazolidine-2-thione-kS)cobalt(II) was synthesized by incorporating a heterocyclic thionate ligand. Crystal structure of the compound consisted of monomer units of CoII atom coordinated to two 1,propyli
Castro, Jesus,Lourido, Paulo Perez,Sousa-Pedrares, Antonio,Labisbal, Elena,Piso, Jose,Garcia-Vazquez, Jose Arturo
p. m319-m322
(2007/10/03)

The thermodynamic properties of CoCl2-NaBr and CoCl2-KBr melts
Boiling temperatures were measured at different pressures for CoCl2-NaBr and CoCl2-KBr melts of various compositions by the method of boiling points under isobaric conditions. The experimental data were described by the equation log p = B - A/T. Dependences with negative deviations from the Raoult law were obtained. The thermodynamic properties of the melts were calculated.
Kritskaya,Burylev,Moisov,Kostenko
p. 911 - 914
(2007/10/03)

New polyfunctional silicon-containing amines C6[CH 2CH2SiMe(OCH2CH2NR2) 2]6 (R = H, Me) and their reactions with cobalt(II) chloride and dicobalt octacarbonyl
Hexakis[bis(2-aminoethoxy)methylsilylethyl]benzene and hexakis[bis(N,N-dimethyl-2-aminoethoxy)methylsilylethyl]benzene C 6[(NR2CH2CH2O) 2SiMeCH2CH2]6 (4, R = H; 5, R =
Ladilina,Semenov,Mushtina,Lopatin,Kurskii,Kirillov,Domrachev
p. 2277 - 2285
(2007/10/03)

Thermal behaviour of metal complexes of 6-(2-pyridylazo)-3-acetamidophenol
The present work aims chiefly to study the thermal behaviour of complex compounds with general formula: [M(HL)·xH2O](A)·yH2O (where HL=C13H11N4O2=6-(2-pyridylazo)-3-ace tamidophenol (PAAP), M=Cu(II), Zn(II), Cd(II) and Fe(III) x=1, 3; y=2, 5) while A=CH3COO- (Ac), Cl2. The second formula is [M(H2L)·xH2O]Cl2·yH2O, (where H2L=C13H12 N4O2 (PAAP), M=Ni(II), Co(II) x=3; y=4, 6). The compounds were identified by elemental analysis, FT-IR spectra and TG/DTG, DTA methods. It was found that during the thermal decomposition of complex compounds water molecules of crystallization are released in the first step. In the next step the pyrolysis of organic ligand takes place. Metal oxide remained as a solid product of the thermal decomposition. Mass spectroscopy has been used for the determination of the thermal decomposition on the intermediate products. It was found the thermal stability of the studied compounds increases as the ionic radii decreases. The activation energy E, the entropy change ΔS*, the enthalpy ΔH* change and Gibbs free energy change ΔG* were calculated from TG curve.
Mohamed,Nour El-Dien,El-Gamel, Nadia E.A.
p. 135 - 146
(2008/10/08)

Thermal and spectral studies of binary complexes of cyanodithioformate with transition metal ions
Binary complexes of the type [M(S2CCN)2] (M = Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) have been synthesised from alcoholic solutions. They have been characterised using elemental analyses, IR, UV-VIS spectroscopy, magnetic susceptibility measurement and solution conductance data. In thermogravimetry (TG) studies, all these complexes exhibit a prominent weight loss step between 100 and 330 °C under a N2 atmosphere. Besides, a second weight loss step has also been observed beyond 800° C for the Mn2+, Fe2+ and Co2+ complexes, between 400 and 600 °C for Zn2+ complex and beyond 380 °C for Cu2+ complex. Broad differential thermal analysis (DTA) endotherms are observed corresponding to these weight loss steps. The first weight loss in the TG scan of the complexes follows a deceleratiory α-time curve with D3 mechanism for all complexes. The activation energy (Ea) for the thermal decomposition varies between 43 and 115 kJ/mol and removal of CS2 and/or CS have been suggested. Various decomposition parameters have been calculated.
Prasad, Rajendra,Kumar, Azad
p. 59 - 67
(2008/10/08)

Thermoelectric power of delafossite-type metallic oxide PdCoO2
Thermoelectric power of metallic cobalt oxide PdCoO2, of which Co valence is 3+ in the low spin state and the density of state at the Fermi level is dominated by Pd 4d electrons, has been clarified between 100 and 400K. It is found that the temperature dependence of thermoelectric power shows a gradual change. The values of thermoelectric power in the measured temperature range are 2-4μV/K. These values comparable to normal conventional metals may be attributable to the Fermi level just at the bottom of the deep cave of the density of state.
Hasegawa, Masashi,Inagawa, Ikuo,Tanaka, Masayuki,Shirotani, Ichimin,Takei, Humihiko
p. 203 - 205
(2008/10/08)