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Cobalt Complex (cobalt + complex)
Selected AbstractsChemInform Abstract: Highly Enantioselective Carbonyl-ene Reactions Catalyzed by a Hindered Silyl,Salen,Cobalt Complex.CHEMINFORM, Issue 12 2008Gerri E. Hutson Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Dinuclear Manganese and Cobalt Complexes with Cyclic Polyoxovanadate Ligands: Synthesis and Characterization of [Mn2V10O30]6, and [Co2(H2O)2V10O30]6,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 34 2009Shinnosuke Inami Abstract An all-inorganic complex, [Mn2{(VO3)5}2]6, (1), was synthesized, and the structure determination reveals a dinuclear manganese complex coordinated by two cyclic pentavanadate ligands. The cyclic pentavanadate units sandwich the edge-sharing octahedral dimanganese core through coordination of the oxido group of the pentavanadate. A dinuclear cobalt complex with a cyclic decavanadate, [Co2(OH2)2(VO3)10]6, (2), was also synthesized. The structure analysis reveals a dinuclear cobalt complex with a macrocyclic decavanadate, which is composed of 10 VO4 units joined by the vertex sharings. The CoO6 octahedrons are edge-shared, with each cobalt octahedron coordinated to five oxido groups from the decavanadate. The remaining site is occupied by water. The coordinated water molecules are supported with hydrogen bonds in two directions. Complex 2 in acetonitrile shows no reactivity with dioxygen even at low temperature, and the cyclic voltammogram of 2 shows no redox chemistry in acetonitrile. Complex 2 exhibits chromism by water exposure both in the solid state and in acetonitrile. Complex 2 is green,yellow in color, and the addition of water causes the complex to turn brown. After heating the sample, it returns to its original color in a reversible manner. The EXAFS data in acetonitrile is also reported and is consistent with the solid-state structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] ChemInform Abstract: Study of the Recycling Possibilities for Azabis(oxazoline),Cobalt Complexes as Catalysts for Enantioselective Conjugate Reduction.CHEMINFORM, Issue 31 2010Luis Aldea Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Enantioselective Borodeuteride Reduction of Aldimines Catalyzed by Cobalt Complexes: Preparation of Optically Active Deuterated Primary Amines.CHEMINFORM, Issue 4 2004Daichi Miyazaki Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Reductive Desymmetrization of 2-Alkyl-1,3-diketones Catalyzed by Optically Active ,-Ketoiminato Cobalt Complexes.CHEMINFORM, Issue 49 2001Yuhki Ohtsuka Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Triple-Decker Iron and Cobalt Complexes with a Central Tetramethylphospholyl Ligand.CHEMINFORM, Issue 12 2001A. R. Kudinov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Secondary Synthesis of Two Cobalt Complexes by the Use of 5-Sulfosalicylate and 1,10-Phenanthroline and Their Crystal StructuresCHINESE JOURNAL OF CHEMISTRY, Issue 10 2005Sai-Rong Fan Abstract Cobalt(II) nitrate reacted with 1,10-phenanthroline (phen) and 5-sulfosalicylic acid (H3ssal) to yield the cobalt(II) complex [Co(phen)2(H2O)2](Hssal)·4H2O (1) and the reaction of 1 with copper acetate led to a novel complex [Co(phen)(H2O)4][Cu2(ssal)2(phen)2]·5H2O (2). These two complexes were cation-anion species and the cationic motif [Co(phen)2(H2O)2]2+of 1 could be converted to [Co(phen)(H2O)4]2+ in the formation process of new anion [Cu2(phen)2(ssal)2]2, of 2. In both complexes abundant hydrogen bonds construct different supramolecular architectures, thus the conversion reaction can provide a new path to create novel supramolecular network. [source] Vinylic and ring-opening metathesis polymerization of norbornene with bis(,-ketoamine) cobalt complexes,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2005Feng Bao Abstract Cobalt complexes 1,4 bearing N,O -chelate ligands based on condensation products of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone with aniline, o -methylaniline, ,-naphthylamine, and p -nitroaniline, respectively, were synthesized, and the structures of 1 and 4 were characterized by single-crystal X-ray diffraction analyses. The bis(,-ketoamine) cobalt complexes could act as moderately active catalyst precursors for norbornene polymerization with the activation of methylaluminoxane. This catalytic reaction proceeded mainly through a vinyl-type polymerization mechanism. 1H NMR and IR showed that in all cases, a small amount of double bonds raised from ring-opening metathesis polymerization (ROMP) was present in the polymerization products. The variation of the polymerization conditions affected the ROMP unit ratio in the polynorbornenes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5535,5544, 2005 [source] Synthesis and Physicochemical Characterization of Bis(macrocycles) Involving a Porphyrin and a meso -Substituted Corrole , X-ray Crystal Structure of a [(Free-base porphyrin),corrole]bis(pyridine)cobalt ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2005Jean-Michel Barbe Abstract A very efficient, simple synthesis of face-to-face porphyrin,corrole free-bases bearing substituents at the meso positions of the corrole ring is reported. Starting from the (porphyrin,aldehyde)zinc species 1Zn, porphyrin,corrole free-bases (3M, 3C) are obtained in two steps, in fairly good yields (40,43,%), compared to 11 steps for their corrole ,-pyrrole-substituted counterparts. Moreover, the possibility to directly synthesize the free-base (porphyrin,corrole)cobalt complex (5M or 5C) allows for the further preparation of heterodimetallic derivatives. Crystals of the bis(pyridine) adduct of 5M have been grown; the molecular structure clearly shows that the two pyridine molecules are coordinated to the cobalt ion in endo and exo positions, leading to an open-mouth geometry of the bis(macrocycle). The structure of 5M(py)2also shows intermolecular ,,, interactions along the [1,0,0] direction, leading to stacking of the complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Modes of Reactivity of Cyclic Diynes: Probing the syn/anti Selectivity of Tetrathiacycloalkadiynes and Mono(alkyne)cobalt ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2003Christoph Benisch Abstract Cyclic tetrathiaalkadiynes in which two 1,4-dithiaalkyne units are connected with alkane bridges of length n and m [A(m.n)] were treated with [,2 -bis(tert -butylsulfonyl)acetylene]carbonyl(,5 -cyclopentadienyl)cobalt(I) (8a) and several substituted analogues (8b,8e) in order to probe the reactivity of electron-rich cyclic diynes. Both mono- [B(m.n)] and bis(cyclobutadiene) [C(m.n)] complexes were isolated as products of these reactions and the anti/syn ratio of C(m.n) was determined. For m, n < 4 the syn isomers dominate and this is attributed to the configuration of the intermediate metallacycle which is correlated with the conformations of the rings in the mono(cyclobutadiene) products B(m.n). This analysis was corroborated by X-ray structural investigations of the products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Synthesis and structure of a new one-dimensional cobalt complex with dicyanamide and 4-picolyl choride bridgesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2006Hongxia Pei Abstract The synthesis and structure of the 1D cobalt (II) complex, [Co(L)2(dca)2] (1) (dca = dicyanamide, C2N3,, L = 4-picolyl choride) is reported. Complex 1 crystallized in triclinic system, space group P -1, with cell dimensions of a = 7.291(2) Å, b = 7.481(2) Å, c = 9.007(3) Å, , =104.444(4)°, , = 96.971(4)°, , =102.618(4)°, V = 456.1(2) Å3, Z = 1, Dc = 1.624 Mg/m3. In complex 1, Co (II) is 6-coordinated by N atoms of four dca ligands and two L ligands. The centrosymmetric CoN6 chromophore is an axially elongated octahedron that has Co-N distances ranging from 2.122(3) to 2.154(3) Å. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis, crystal structure and characterization of new transition metal compounds of bromophenols: Bis(2,4,6-tribromophenolato) di(N-methylimidazole)M(II) (M=Co, Cu)CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2005P. Camurlu Abstract Bis(2,4,6-tribromophenolato)di(N-methyl imidazole)M(II), where M stands for cobalt and copper metals, was synthesized via reaction of the corresponding metal sulphate and 2,4,6-tribromophenolate in aqueous media in the presence of N-methyl imidazole and sodium hydroxide. Although various crystallization procedures were applied only cobalt complex was obtained as single crystals. The Co(II) ion has a distorted octahedral enviroment involving two O atoms and two N atoms of the Bis(2,4,6-tribromophenolato)di(N-methyl imidazole) ligand. Powder x-ray diffraction pattern of copper compound was used for cooper complex. For characterizations of complexes carbon, hydrogen and nitrogen elemental analysis, FTIR and UV spectroscopy, DSC thermal analysis and magnetic susceptibility measurements at room temperature were performed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dinuclear Manganese and Cobalt Complexes with Cyclic Polyoxovanadate Ligands: Synthesis and Characterization of [Mn2V10O30]6, and [Co2(H2O)2V10O30]6,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 34 2009Shinnosuke Inami Abstract An all-inorganic complex, [Mn2{(VO3)5}2]6, (1), was synthesized, and the structure determination reveals a dinuclear manganese complex coordinated by two cyclic pentavanadate ligands. The cyclic pentavanadate units sandwich the edge-sharing octahedral dimanganese core through coordination of the oxido group of the pentavanadate. A dinuclear cobalt complex with a cyclic decavanadate, [Co2(OH2)2(VO3)10]6, (2), was also synthesized. The structure analysis reveals a dinuclear cobalt complex with a macrocyclic decavanadate, which is composed of 10 VO4 units joined by the vertex sharings. The CoO6 octahedrons are edge-shared, with each cobalt octahedron coordinated to five oxido groups from the decavanadate. The remaining site is occupied by water. The coordinated water molecules are supported with hydrogen bonds in two directions. Complex 2 in acetonitrile shows no reactivity with dioxygen even at low temperature, and the cyclic voltammogram of 2 shows no redox chemistry in acetonitrile. Complex 2 exhibits chromism by water exposure both in the solid state and in acetonitrile. Complex 2 is green,yellow in color, and the addition of water causes the complex to turn brown. After heating the sample, it returns to its original color in a reversible manner. The EXAFS data in acetonitrile is also reported and is consistent with the solid-state structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Reactivity of the [,2 -Bis(tert -butylsulfonyl)acetylene](carbonyl)(,5 -cyclopentadienyl)cobalt Complex Towards Electron-Rich and -Poor Acetylenes,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2005Avijit Goswami Abstract The electron-rich aminoacetylenes Et2NC2R (2a,c, R = SPh, PPh2, and Ph, respectively) react smoothly with [,2 -bis(tert -butylsulfonyl)acetylene](carbonyl)(,5 -cyclopentadienyl)co-balt (1) to form the donor,acceptor stabilized (,4 -cyclobutadiene)cobalt complexes 3a,c in good yields. However, treatment of the electron-poor borylacetylenes 2d,f with the cobalt complex 1 does not lead to the expected (,4 -cyclobutadiene)cobalt complexes. Analogously, the reaction of bis(1-phenylethynyl)sulfide (2g) with two equivalents of 1 gives rise to the sulfur-bridged bis[,4 -(cyclobutadiene)cobalt] complex 3g. The new cobalt complexes were characterized by NMR spectroscopy, mass spectrometry, and by X-ray structure analysis for 3a, which reveals almost equal C,C bond lengths within the cyclobutadiene ring. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis and Physicochemical Characterization of Bis(macrocycles) Involving a Porphyrin and a meso -Substituted Corrole , X-ray Crystal Structure of a [(Free-base porphyrin),corrole]bis(pyridine)cobalt ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2005Jean-Michel Barbe Abstract A very efficient, simple synthesis of face-to-face porphyrin,corrole free-bases bearing substituents at the meso positions of the corrole ring is reported. Starting from the (porphyrin,aldehyde)zinc species 1Zn, porphyrin,corrole free-bases (3M, 3C) are obtained in two steps, in fairly good yields (40,43,%), compared to 11 steps for their corrole ,-pyrrole-substituted counterparts. Moreover, the possibility to directly synthesize the free-base (porphyrin,corrole)cobalt complex (5M or 5C) allows for the further preparation of heterodimetallic derivatives. Crystals of the bis(pyridine) adduct of 5M have been grown; the molecular structure clearly shows that the two pyridine molecules are coordinated to the cobalt ion in endo and exo positions, leading to an open-mouth geometry of the bis(macrocycle). The structure of 5M(py)2also shows intermolecular ,,, interactions along the [1,0,0] direction, leading to stacking of the complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Granisetron, an antiemetic drug, and its cobalt complexACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2010Krishnan Ravikumar The crystal structures of granisetron [systematic name: 1-methyl- N -(9-methyl-9-azabicyclo[3.3.1]nonan-7-yl)indazole-3-carboxamide], C18H24N4O, (I), an antinauseant and antiemetic agent, and its CoII complex, diaqua[1-methyl- N -(9-methyl-9-azoniabicyclo[3.3.1]nonan-7-yl)indazole-3-carboxamide]cobalt(II) tetrachloride dodecahydrate, [Co(C18H25N4O)2(H2O)2]Cl4·12H2O, (II), have been determined by X-ray diffraction. The granisetron molecule is in an extended conformation in both structures. Twisting of the central carboxamide group facilitates the CoII coordination in (II). The CoII atom is located on an inversion centre. The azabicyclononane ring adopts a chair,boat conformation in both structures. The molecules in (I) are linked into centrosymmetric dimers and form tetracyclic rings through C,H...O hydrogen-bonding interactions. The simultaneous presence of free chloride ions in conjunction with a number of hydration water molecules in (II) provides interesting hydrogen-bond patterns. This study can aid in the investigation of the properties of metal complexes with active pharmaceuticals in which the drug molecules play the role of a ligand. [source] ChemInform Abstract: Supported Cobalt Complex-Catalyzed Conjugate Addition of Indoles, Amines and Thiols to ,,,-Unsaturated Compounds.CHEMINFORM, Issue 42 2010Fatemeh Rajabi Abstract A supported cobalt complex is successfully used as a reusable catalyst for the Michael addition of thiols (I), amines (VI), and indoles (VIII) to alkenes (II) and (IV) under solvent-free conditions. [source] A Chemical Device That Exhibits Dual Mode Motions: Dynamic Coupling of Amide Coordination Isomerism and Metal-Centered Helicity Inversion in a Chiral Cobalt(II) ComplexCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2008Hiroyuki Miyake Prof. Chemical hand-waving: Dynamic molecular motion between two distinct structures (contraction/extension) is displayed by an octahedral cobalt complex (shown schematically), in which the distance between two coordinated methoxy oxygen atoms changed from 0.3 to 1.3,nm. Furthermore, the helical direction of the extended complex was inverted in response to NO3, ions, and stretching and inverting motions occurred reversibly and repeatedly. [source] Synthesis, Crystal Structure of Co(II)(6-methoxybenzothiazole- 2-carboxylate)2(DMF)2 and Its Application to Carbonylation of Benzyl ChlorideCHINESE JOURNAL OF CHEMISTRY, Issue 1 2010Bin Zhang Abstract A new complex, Co(MBTC)2(DMF)2 (MBTC=6-methoxybenzothiazole-2-carboxylate, DMF=N,N -dime- thylformamide), was synthesized in DMF solution and characterized by single crystal X-ray diffraction analysis. Using the cobalt complex as catalyst, phenylacetic acid was prepared by the carbonylation of benzyl chloride with carbon monoxide (0.1 MPa). The effects of solvents, phase transfer catalysts and temperature on the reactions were investigated. The yield of phenylacetic acid was higher than 90% in optimized condition. [source] Cobalt and Nickel Complexes Bearing Pyrazolyliminophosphorane Ligands: Synthesis, Characterisation and Catalytic Ethylene Oligomerisation BehaviourEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2006Cheng Zhang Abstract Treatment of 1-(2,-azidophenyl)-3,5-dimethylpyrazole (1) with Ph2PR (R = Ph, Me) and (Ph2P)2CH2, respectively, affords the pyrazolyliminophosphoranes 2, 3 and 4. Reaction of 2 or 3 with [NiCl2(dme)] or NiBr2 yields the N,N-chelate nickel complexes 5,8, and with CoCl2 complexes 9 and 10. Reaction of 4 with [NiCl2(dme)], NiBr2 and CoCl2, respectively, affords the N,N,P-chelate complexes 11,13. Compounds 2,4 were characterised by 1H, 13C, 31P NMR and IR spectroscopy and elemental analysis, while complexes 5,13 were characterised by IR spectroscopy and elemental analysis. The structures of complexes 5, 9 and 12 were further characterised by single-crystal X-ray diffraction techniques. Complexes 5,13 are active catalysts for ethylene oligomerisation upon activation with alkylaluminium derivatives(Et2AlCl, MAO or MMAO). These complexes exhibit good to high catalytic activities (up to 3.54,×,106 g,mol,1,h,atm for the nickel complexes and 5.48,×,105 g,mol,1,h,atm for the cobalt complexes). The effects of varying ethylene pressure, temperature and aluminium co-catalyst/Ni or Co ratios with complexes 5, 9, 11 and 12 are reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Reactivity of the [,2 -Bis(tert -butylsulfonyl)acetylene](carbonyl)(,5 -cyclopentadienyl)cobalt Complex Towards Electron-Rich and -Poor Acetylenes,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2005Avijit Goswami Abstract The electron-rich aminoacetylenes Et2NC2R (2a,c, R = SPh, PPh2, and Ph, respectively) react smoothly with [,2 -bis(tert -butylsulfonyl)acetylene](carbonyl)(,5 -cyclopentadienyl)co-balt (1) to form the donor,acceptor stabilized (,4 -cyclobutadiene)cobalt complexes 3a,c in good yields. However, treatment of the electron-poor borylacetylenes 2d,f with the cobalt complex 1 does not lead to the expected (,4 -cyclobutadiene)cobalt complexes. Analogously, the reaction of bis(1-phenylethynyl)sulfide (2g) with two equivalents of 1 gives rise to the sulfur-bridged bis[,4 -(cyclobutadiene)cobalt] complex 3g. The new cobalt complexes were characterized by NMR spectroscopy, mass spectrometry, and by X-ray structure analysis for 3a, which reveals almost equal C,C bond lengths within the cyclobutadiene ring. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Vinylic and ring-opening metathesis polymerization of norbornene with bis(,-ketoamine) cobalt complexes,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2005Feng Bao Abstract Cobalt complexes 1,4 bearing N,O -chelate ligands based on condensation products of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone with aniline, o -methylaniline, ,-naphthylamine, and p -nitroaniline, respectively, were synthesized, and the structures of 1 and 4 were characterized by single-crystal X-ray diffraction analyses. The bis(,-ketoamine) cobalt complexes could act as moderately active catalyst precursors for norbornene polymerization with the activation of methylaluminoxane. This catalytic reaction proceeded mainly through a vinyl-type polymerization mechanism. 1H NMR and IR showed that in all cases, a small amount of double bonds raised from ring-opening metathesis polymerization (ROMP) was present in the polymerization products. The variation of the polymerization conditions affected the ROMP unit ratio in the polynorbornenes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5535,5544, 2005 [source] Effect of cyanoguanidine-metal and urea-metal complexes on the thermal degradation of poly(vinyl chloride)JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2010Abir S. Abdel-Naby Tin, nickel, cobalt, zinc, and copper complexes of cyanoguanidine and urea were synthesized and investigated as thermal stabilizers for rigid poly(vinyl chloride) at 180°C in air. Their stabilizing efficiencies were evaluated by measuring the induction period (the period during which no evolved hydrogen chloride could be detected) and the rate of dehydrochlorination as determined by continuous potentiometric measurements, in addition to the extent of discoloration. The results clearly revealed the greater efficiency of all of the investigated metal complexes as compared to those of well-recognized reference stabilizers. The tin complex always exhibited the highest efficiency irrespective of the type of ligand used. The nickel and cobalt complexes also possessed high stabilizing efficiencies. The order of the stabilizing potency of the various metal complexes was Sn , Co, Ni , Zn, Cu. Combining the ligand itself with dimethyltin- s,s,-bis (isooctyl thioglycolate), as a reference stabilizer containing a tin atom, led to a true synergism. This synergistic effect might be attributed to the formation in situ of a complex between the ligand and the tin atom. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers [source] Studies on Energetic Compounds Part,27: Kinetics and Mechanism of Thermolysis of Bis(Ethylenediamine)Metal Nitrates and Their Role in the Burning Rate of Solid PropellantsPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 5 2003Gurdip Singh Abstract Four bis(ethylenediamine)metal(II) nitrate (BEMN) complexes, i.e. [M(EDA)2](NO3)2, where M=Cu, Co, Ni and Zn, have been prepared and characterized. Thermolysis of these complexes induced by heat and drop-weight impact has been investigated by TG-DTG, DTA, explosion delay (DE), explosion temperature (TE) and impact sensitivity measurement. The kinetics of early thermolysis reaction prior to fast decomposition have been evaluated. Contracting area (CA, n=2) and contracting cube (CC, n=3) equations were found to give the best fits in isothermal TG data among all tested nine mechanism-based kinetic models. The values of activation energy (Ea), TE, DE and activation energy for explosion (E*) have been found to be quite lower for the copper complex as compared to cobalt, nickel and zinc complexes. A mechanism of thermolysis has also been proposed. All these complexes were found to be insensitive towards impact of 2,kg weight up to the height of 110,cm. These complexes were used as energetic burning rate modifiers in the combustion of hydroxy-terminated polybutadiene (HTPB)-ammonium perchlorate (AP) composite solid propellants. A two-fold increase in burning rate was observed with copper and cobalt complexes at low concentration (2% by wt.). The in situ freshly formed metal oxides with large number of active sites in their crystallites seem to be better additives for combustion of propellants. [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] Direct observation of deuterium migration in crystalline-state reaction by single-crystal neutron diffraction.ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2001The H atoms bonded to the chiral C atoms (stereogenic center) of the 1-cyanoethyl groups in two cobalt complexes, [(R)-1-cyanoethyl]bis(dimethylglyoximato)(pyridine)cobalt(III) (2) and [(R,S)-1-cyanoethyl]bis(dimethylglyoximato)(piperidine)cobalt(III) (3), were replaced with D atoms, such as Co,C*D(CH3)CN. The crystals of the two cobalt complexes were irradiated with a xenon lamp for 72,h and 27,d, respectively. The unit-cell dimensions were gradually changed with retention of the single-crystal form. The crystal structures after irradiation were determined by neutron diffraction. In each crystal the chiral 1-cyanoethyl group of one of the two crystallographically independent molecules was partly inverted to the opposite configuration, whereas that of the other molecule kept the original configuration. The C*,D bond in the inverted group was completely conserved in the process of the inversion of the chiral alkyl group. This suggests that the inversion of the chiral 1-cyanoethyl group proceeds with the rotation of the cyanoethyl radical after the Co,C bond cleavage by photo-irradiation so that the opposite side of the radical faces the Co atom. This is followed by recombination of the Co,C bond to form the inverted 1-cyanoethyl group. [source] Synthesis reactivity and electrochemical properties of substituted cyclopentadienyl cobalt (III) complexesCHINESE JOURNAL OF CHEMISTRY, Issue 5 2000Xiu-Feng Hou Abstract Cyclopentadienyl cobalt complexes (,5 -C5H4R) CoLI2 [L = CO,R=-COOCH2CH=CH2 (3); L=PPh3, R=-COOCH2 -CH=CH2 (6); L=P(p-C6H4O3)3, R = -COOC(CH3) = CH2 (7), -COOCH2C6H5 (8), -COOCH2CH = CH2 (9)] were prepared and characterized by elemental analyses, 1H NMR, ER and UV-vis spectra. The reaction of complexes (,5 -C5H4R)CoLI2 [L= CO, R= -COOC(CH3) = CH2 (1), -COOCH2C6H5(2); L=PPh3, R=-COOC (CH3) = CH2 (4), -COOCH2C6H5 (5)] with Na-Hg resulted in the formation of their corresponding substituted cobaltocene (,5 -C5H4R)2 Co[R=-COOC(CH3) = CH2 (10), -COOCH2C6H5 (11)]. The electrochemical properties of these complexes 1,11 were studied by cyclic voltammetry. It was found that as the ligand (L) of the cobalt (III) complexes changing from CO to PPh3 and P(p -tolyl)3, their oxidation potentials increased gradually. The cyclic voltammetry of ,,,,-substituted cobaltocene showed reversible oxidation of one electron process. [source] | |||||||||||||||||||||||||