- The Role of Iodanyl Radicals as Critical Chain Carriers in Aerobic Hypervalent Iodine Chemistry
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Selective O2 utilization remains a substantial challenge in synthetic chemistry. Biological small-molecule oxidation reactions often utilize aerobically generated high-valent catalyst intermediates to effect substrate oxidation. Available synthetic methods for aerobic oxidation catalysis are largely limited to substrate functionalization chemistry by low-valent catalyst intermediates (i.e., aerobically generated Pd(II) intermediates). Motivated by the need for new chemical platforms for aerobic oxidation catalysis, we recently developed aerobic hypervalent iodine chemistry. Here, we report that in contrast to the canonical two-electron oxidation mechanisms for the oxidation of organoiodides, the developed aerobic hypervalent iodine chemistry proceeds via a radical chain mechanism initiated by the addition of aerobically generated acetoxy radicals to aryl iodides. Despite the radical chain mechanism, aerobic hypervalent iodine chemistry displays substrate tolerance similar to that observed with traditional terminal oxidants, such as peracids. We anticipate that these insights will enable new sustainable oxidation chemistry via hypervalent iodine intermediates. O2 is routinely utilized in biological catalysis to generate high-valent catalyst intermediates that engage in substrate oxidation chemistry. Analogous synthetic chemistry via aerobically generated high-valent intermediates would enable new sustainable synthetic methods but is largely unknown because of the challenges in selective O2 utilization. We have developed aerobic hypervalent iodine chemistry as a platform for coupling O2 reduction with a diverse set of substrate functionalization mechanisms. Many of the synthetic applications of hypervalent iodine reagents rely on selective two-electron oxidation-reduction chemistry. Here, we report that one-electron oxidation reactions pathways via iodanyl radical intermediates are critical in aerobic hypervalent iodine chemistry. The new appreciation for the critical role that iodanyl radicals can play in the synthesis of hypervalent iodine compounds will provide new opportunities in sustainable oxidation catalysis. Aerobic hypervalent iodine chemistry provides a strategy for coupling the one-electron chemistry of O2 with two-electron processes typical of organic synthesis. We show that in contrast to the canonical two-electron oxidation of aryl iodides, aerobic synthesis proceeds by a radical chain process initiated by the addition of aerobically generated acetoxy radicals to aryliodides to generate iodanyl radicals. Robustness analysis reveals that the developed aerobic oxidation chemistry displays substrate tolerance similar to that observed in peracid-based methods and thus holds promise as a sustainable synthetic method.
- Hyun, Sung-Min,Yuan, Mingbin,Maity, Asim,Gutierrez, Osvaldo,Powers, David C.
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supporting information
p. 2388 - 2404
(2019/09/12)
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- Co(II)-salen catalyzed stereoselective cyclopropanation of fluorinated styrenes
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Three cis-selective Co(II)-salen complexes have been developed for the asymmetric cyclopropanation of para-fluorinated styrenes with ethyl diazoacetate. Increasing the steric reach of the C2-symmetric ligand side chains improved the enantiomeric ratio of the reaction from 28:1 to 66:1. The methodology was exemplified by the gram-scale synthesis of a lead compound for the treatment of castration-resistant prostate cancer (CRPC), as well as a structurally related analog.
- Tai, Serene,Maskrey, Taber S.,Nyalapatla, Prasanth R.,Wipf, Peter
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p. 1014 - 1027
(2019/11/14)
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- The Kinetics of Growth of Metallo-supramolecular Polyelectrolytes in Solution
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Several transition metal ions, like Fe2+, Co2+, Ni2+, and Zn2+ complex to the ditopic ligand 1,4-bis(2,2′:6′,2′′-terpyridin-4′-yl)benzene (L). Due to the high association constant, metal-ion induced self-assembly of Fe2+, Co2+, and Ni2+ leads to extended, rigid-rod like metallo-supramolecular coordination polyelectrolytes (MEPEs) even in aqueous solution. Here, we present the kinetics of growth of MEPEs. The species in solutions are analyzed by light scattering, viscometry and cryogenic transmission electron microscopy (cryo-TEM). At near-stoichiometric amounts of the reactants, we obtained high molar masses, which follow the order Ni-MEPE≈Co-MEPEa reversible step-growth mechanism. The forward polymerization rate constants follow the order Co-MEPEFe-MEPENi-MEPE and the growth of MEPEs can be accelerated by adding potassium acetate.
- Munzert, Stefanie Martina,Stier, Simon P.,Schwarz, Guntram,Weissman, Haim,Rybtchinski, Boris,Kurth, Dirk G.
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p. 2898 - 2912
(2017/10/06)
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- Kinetic stability of complexes of some d-metals with 3,3'- bis(dipyrrolylmethene) in the binary proton-donor solvent acetic acid-benzene
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The kinetics of dissociation of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) binuclear homoleptic double-stranded helicates with bis(2,4,7,8,9- pentametyldipyrrolylmethen-3-yl)methane (H2L) of the [M 2L2] composition
- Antina,Guseva,V'yugin,Antina
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p. 1293 - 1297
(2013/01/14)
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- Structural, spectral and magnetic properties of carboxylato cobalt(II) complexes with heterocyclic N-donor ligands: Reconstruction of magnetic parameters from electronic spectra
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Heteroleptic cobalt(II) complexes with general formula of [Co(N-base) 2(car)2(H2O)2], have been synthesized and structurally characterized; the N-base stands for neutral N-donor ligands: iso-quinoline (iqu), [1]
- Titis,Hudak,Kozisek,Krutosikova,Moncol',Tarabova,Boca
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p. 106 - 113
(2012/07/14)
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- Kinetics and products of the catalytic oxidation of acetamidotoluenes with ozone in acetic acid
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The kinetics of acetamidotoluene oxidation in glacial acetic acid in the presence of cobalt acetate is reported. At 95°C and atmospheric pressure, acetamidotoluenes are oxidized by molecular oxygen very slowly: oxidation is complete in 10-12 h, and the major reaction products are acetamidobenzoic acids (27-36% yield). The introduction of ozone into the reactive gas increases the reaction rate by one order of magnitude. The main role of ozone is to generate the active form of the catalyst.
- Galstyan,Bushuev,Sementsov
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p. 516 - 520
(2011/01/07)
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- Factors affecting the selectivity of the oxidation of methyl p-toluate by cobalt(III)
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The anaerobic oxidation of methyl p-toluate by cobalt(III) in acetic acid was investigated. Observed products were 4-carbomethoxybenzaldehyde (2), 4-carbomethoxybenzoic acid (3), 4-carbomethoxybenzyl acetate (1), 4,4′-dicarbomethoxybibenzyl (6), methyl 2,4-dimethylbenzoate (8), and methyl 3,4-dimethylbenzoate (9). Deuterium isotope labeling showed that 2 was not formed from 1, but appeared to be formed directly from methyl p-toluate via 4-carbomethoxybenzyl alcohol (5). The ratio of (2 + 3) to 1 was 0.5 with [Py3Co3O(OAc)5OH[PF6] and 1.0 with cobaltic acetate. Cobaltic acetate was generated in situ by the reaction of cobaltous acetate and peracetic acid. When the oxidation was carried out in the presence of chromium (0.05 equiv based on cobalt), the ratio increased dramatically and no 6 was observed. Other transition metals such as vanadium, molybdenum, and manganese had a similar effect, but were not as effective as chromium. Chromium was observed to form a mixed-metal cluster complex with cobalt. Treatment of an acetic acid solution of cobaltous acetate and methyl isonicotinate with K2CrO4 produced a solid tentatively identified as [(MIN)3Co2CrO(OAc)6][CrO 4H] (MIN = methyl isonicotinate). The selectivity for the oxidation of methyl p-toluate exhibited by the mixed-metal cluster complex was similar to that observed by the addition of chromium to oxidations using [py 3Co3O(OAc)5OH[PF6].
- Sumner Jr., Charles E.,Morrill, Kent A.,Howell, Jeff S.,Little, James
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p. 2190 - 2195
(2009/01/31)
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- Synthesis and characterization of cobalt (II) complexes of chromen-2-one-3-carboxy hydrazide and 2-(chromen-2′-onyl)-5-(aryl) 1,3,4-oxadiazole derivatives
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Cobalt(II) complexes of chromen-2-one-3-carboxy hydrazide and 2-(chromen 2′-onyl)-5-(aryl)-1,3,4-oxadiazole derivatives have been synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance, spectral studies [IR, UV-vis, and 1H NMR]. All the Co(II) complexes exhibit the composition M(Ln)2X2; where M = Co(II), L1 is chromen-2-one-3-carboxy hydrazide, L2 is 2-(chromen-2′-onyl)-5-(2″- hydroxylphenyl)1,3,4-oxadiazole, L3 2-(chromen-2′-onyl)-5-(4″- nitrophenyl)1,3,4-oxadiazole and L4 is 2-(chromen-2′-onyl)-5-(4″- chlorophenyl)1,3,4-oxadiazole. X = Cl-, Br-, NO 3-, CH3COO- , ClO4 -, CNS-, SO4-. The N,O donor ligands act as a bidentate ligand in all the complexes. Distorted octahedral geometry for all the Co(II) complexes is proposed. X-ray structure determination has been made for the exact definition of the coordination sphere. The newly synthesized Co(II) complexes have been screened for their antimicrobial activity against some bacterial species like E. coli, S. aureus, Pseudomonas aeruginosa and few fungal strains, C. albicans and Cryptococcus neoformans.
- Mathew, Glory,Suseelan,Krishnan
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p. 2040 - 2044
(2007/10/03)
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- Synthesis and characterization of ternary carboxylato complexes of cobalt(II) with Schiff bases
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Some novel mixed-ligand, ternary carboxylato complexes of cobalt(II) with Schiff bases (HSB) having general formula [Co(OOCR)(SB)] (where R = C 11H23, C13H27, C15H 31 or C17H35) have been synthesized by the substitution reactions of anhydrous cobalt(II) acetate. The isolated products have been characterized by elemental analyses, molar conductance and magnetic moment measurements and spectral (infrared, electronic and FAB mass) data. Models and coordination hypotheses for the complexes have been proposed and a peculiar structural characterization has been discussed on the basis of physicochemical studies. A sharp structural change has been noticed.
- Baranwal, Bairam Prasad,Singh, Atresh Kumar,Fatma, Talat,Gupta, Tarkeshwar
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p. 2006 - 2010
(2007/10/03)
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- Racemic and chiral expanded salen-type complexes derived from biphenol and binaphthol: Salbip and salbin
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The reaction of 2-fluoronitrobenzene with 2,2′-biphenol or (R)-binaphthol, followed by reduction and subsequent reaction of the resulting diamine with two equivalents of a salicylaldehyde, affords expanded salen-type ligands having backbones based on biphenol or binaphthol: salbipH2, (R)-salbinH2 and (R)-salbin(t-Bu)4H2. Deprotonation of these ligands with sodium methoxide or potassium hydride, followed by metallation with M(OAc)2 (M = Mn, Co, Ni, or Cu), affords the corresponding metal complexes in good yield (61-85%). The species containing Mn, Co, and Ni all have distorted octahedral geometry, as determined by X-ray crystallography. The ethereal oxygen atoms occupy two coordination sites with metal-oxygen distances ranging from 2.19 to 2.36 ?. The imine nitrogen atoms are trans to each other in the solid state, an impossible geometry in traditional salen-type complexes. The species containing Cu are distorted square planar and show much longer metal-ethereal oxygen distances ranging from 2.79 to 3.22 ?. The manganese complexes are competent catalysts for the epoxidation of olefins.
- Grill, Joseph M.,Reibenspies, Joseph H.,Miller, Stephen A.
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p. 3009 - 3017
(2007/10/03)
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- Method for producing optically active lactone compounds by using salen cobalt complexes having a cis-beta structure
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A method for producing an optically active lactone compound by Baeyer-Villiger oxidation of a cyclic ketone compound with at least one kind of oxidants selected from the group consisting of hydrogen peroxide and urine-hydrogen peroxide adduct (UHP) using a cobalt(salen) complex having a cis-β structure expressed by the following formula (I) or (II) as a catalyst. in which X and Y independently denote H, a t-butyl group or an electron-withdrawing substituting group and W is a halogen element. in which X and Y independently denote H, a t-butyl group or an electron-withdrawing substituting group and Z? is a monovalent anion. The optically active lactone compounds can be used for the synthesis of medicines and argochemicals.
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- Kinetics of the Dissociation of Transition Metal Complexes with α,α-Dipyrrolylmethene in Acetic Acid-Benzene as a Binary Proton-Donating Solvent
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The kinetics of the dissociation of Co(II), Ni(II), and Zn(II) complexes with 4,4′-dibutyl-3,3′,5,5′-tetramethyldipyrrol-2,2′- ylmethene was studied in acetic acid-benzene as a binary proton-donating solvent. The metal nature was found to affect the kinetic parameters of the process. Assumptions were made about the limiting step of the process and the effectiveness of d metal ions in the template synthesis of porphyrins from dipyrrolylmethenes.
- Guseva,Antina,Berezin
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p. 690 - 693
(2008/10/08)
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- New asymmetric catalysis by (salen)cobalt(III) complexes (salen = [bis(salicylidene)ethylenediaminato] = {{2,2′-[ethane-1,2-diyl]bis[(nitrilo-κN) methylidyne]bis[phenolato-κO]}(2-)}) of cis-β-structure: Enantioselective Baeyer-Villiger oxidation of prochiral cyclobutanones
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A series of chiral (salen)cobalt(III) complexes (salen=[bis(salicylidene)ethylenediaminato]={{2,2'-[(ethane-1, 2-diyl)bis[(nitrilo-κN)methylidyne]bis[phenolato-κ0]}(2-)}) of cis-β structure were prepared and used for the enantioselective Baeyer-Villiger oxidation of prochiral cyclobutanones with hydrogen peroxide as terminal oxidant. Both cationic (salen)cobalt(III) and neutral iodo(salen)cobalt(III) complexes 3-5 and 7-12, respectively, all having a chiral binaphthalenediamine unit, were found to be effective catalysts for the enantioselective Baeyer-Villiger oxidation (Tables 1, 3, and 4). In particular, complex 8 bearing electron-withdrawing F-atoms showed a good level of enantioselectivity (75-79% ee) in the reactions of 3-arylcyclobutanones (Scheme 4). On the other hand, complex 12 bearing 'Bu groups at C(3) and C(3') and electron-withdrawing NO2 groups at C(5) and C(5') (trivial numbering) exhibited a high enantioselectivity of 98% ee in the reaction of a tricyclic cyclobutanone (Table 4).
- Uchida, Tatsuya,Katsuki, Tsutomu,Ito, Katsuji,Akashi, Suemi,Ishii, Ayako,Kuroda, Tomomi
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p. 3078 - 3089
(2007/10/03)
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- Synthesis and characterization of some trinuclear cobalt(II) thiocarboxylates
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Some cobalt(II) complexes of thiocarboxylic acids with the general composition Co(SOCR′)2 and Co(SOCR′)(OOCR) [where R = C13H27, C15H31 or C17H35 and R′ = CH3 or C6H5] have been synthesized by substitution reactions and characterized by elemental analyses, spectral studies and magnetic moment measurements. The electrical conductance data indicate that (Co(SOCCH3)2 is a 1:2 electrolyte while the other complexes are non-electrolytes. IR spectra show the presence of bidentate and bridging modes of coordination for carboxylate and thiocarboxylate anions, respectively. Electronic spectral data and magnetic moment values indicate an octahedral environment around cobalt(II). The plausible structure for the trimeric species has been proposed on the basis of the physico-chemical studies. Thermoanalytical data indicate the complexes are stable upto 175°C, above which decomposition starts.
- Baranwal,Gupta, Tarkeshwar
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p. 1855 - 1864
(2008/10/08)
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- Immobilized metal complexes in porous organic hosts: Development of a material for the selective and reversible binding of nitric oxide
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Delivery of NO to specific targets is important in fundamental studies and therapeutic applications. Various methods have been reported for delivery of NO in vivo and in vitro; however, there are few examples of systems that reversibly bind NO. Reported herein is the development of a new polymer (P-1[CoII]) that reversibly binds NO. P-1[CoII] has a significantly higher affinity for NO compared to 02, CO2, and CO. The polymer is synthesized by template copolymerization methods and consists of a porous methacrylate network, containing immobilized four-coordinate CoII sites. Binding of NO causes an immediate color change, indicating coordination of NO to the site-isolated CoII centers. The formation of P-1[Co(NO)] has been confirmed by EPR, electronic absorbance, and X-ray absorption spectroscopies. Electronic and X-ray absorbance results for P-1[CoII] and P-1[Co(NO)] show that the coordination geometry of the immobilized cobalt complexes are similar to those of their monomeric analogues and that NO binds directly to the cobalt centers. EPR spectra show that the binding of NO to P-1[CoII] is reversible in the solid state; the axial EPR signal associated with the four-coordinate CoII sites in P-1[CoII] is quenched upon NO binding. At room temperature and atmospheric pressure, 40% conversion of P-1[Co(NO)] to P-1[CoII] is achieved in 14 days; under vacuum at 120 °C this conversion is complete in ~1 h. The binding of NO to P-1[CoII] is also observed when the polymer is suspended in liquids, including water.
- Padden,Krebs,MacBeth,Scarrow,Borovik
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p. 1072 - 1079
(2007/10/03)
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- Study of nickel-cobalt alloy electrodeposition from a sulfamate electrolyte with different anion additives
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The experimental results of the present study show that the composition of the electrodeposited nickel-cobalt alloy in sulfamate electrolytes containing anion additives is influenced in a complicated manner by the concentrations of cobalt(II) ion and citric acid, pH, and applied current density. The operating conditions were found under which the increase in the pH of the solution adjacent to the cathode is inhibited. Citrate anions form a wide variety of complexes with nickel and cobalt. Protonated citrate complexes of nickel(II) and cobalt(II) are apt to be involved in the electrochemical alloying process. Acetate anions serve to buffer the sulfamate solutions. Nickel-cobalt electrochemical alloying leads to an increase in the reaction rate of cobalt at the expense of the nickel reaction rate. The data confirm that inhibition of the more noble metal by the less noble one does not depend on the anion composition of the electrolyte.
- Golodnitsky,Gudin,Volyanuk
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p. 4156 - 4163
(2008/10/08)
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- Bleaching-active metal complexes
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Compounds of the following formula are suitable as activators for peroxy compounds in laundry detergents and cleaning products: [LnMmXp]zYq(1) in which M is manganese in oxidation stage II, III, IV, V and/or VI or cobalt in oxidation stage II and/or III, X is a coordination group or bridging group, Y is a counterion in the corresponding stoichiometric amount to balance a charge z present, where z as the metal complex charge, can be positive, zero or negative, n and m, independently of one another, are integers of from 1 to 4, p is an integer from 0 to 15, q is z/charge of Y L is a ligand of the formula (2) in which substituents R1 to R8 are as defined in the description.
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- Thermochemical reactivity of transition metal acetates and of a novel DMSO solvate of iron(II) acetate in molecular hydrogen
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The thermal decomposition of acetates of the transition metals Fe, Co, Ni, Mn and Cu in molecular hydrogen has been investigated by means of combined thermogravimetry/mass spectrometry, X-ray diffraction, and transmission as well as scanning electron microscopy. In the context of the reproducible preparation of the parent phases, i.e. the hydrated or anhydrous metal(II) acetates, single crystalline Fe3(CH3COO)6(DMSO)2, a novel DMSO solvate of iron(II) acetate, has been isolated and its crystal structure has been determined by means of X-ray diffraction. For the series of metal(II) acetates it has been found that the course of the thermal degradation in molecular hydrogen, in particular the formation of the gaseous products, strongly depends on the transition metal ion present in the parent compound. The detailed characterization of the solid products revealed, that phases exhibiting different catalytic activities and selectivities are formed as micro- or nanocrystalline metals and/or metal oxides.
- Ehrensberger,Schmalle,Oswald,Reller
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p. 139 - 149
(2008/10/09)
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- The chemistry of cobalt acetate - IV.? the isolation and crystal structure of the symmetric cubane, tetrakis[(μ-acetato)(μ3-oxo) (pyridine)cobalt(III)] chloroform solvate, [Co4(μ-O)4(μ-CH3CO2) 4(C5H5N)4] 5CHCl3 and of the dicationic partial cubane, trimeric
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The isolation from cobalt(III) acetate and characterisation by single crystal X-ray diffraction (refined to R = 0.087, Rw = 0 084) of the symmetric neutral cubane, [Co4-(μ3-O)4(μ-CH3CO 2)4(C5H5N)4], and of the hexafluorophosphate salt (refined to R = 0.078, Rw = 0.073) of the trimeric dication, the partial cubane, [Co3(μ3-O)(μ-OH)3(μ-CH 3CO2)(CH3CO2)(C5H 5N)6]2+, are reported. The cubane crystallises as its chloroform solvate, [Co4(μ3-O)4(μ-CH3CO 2)4(C5H5N)4] · 5CHCl3, whilst the partial cubane crystallises as its water solvate, [Co3(μ,-O)(μ-OH)3(μ-CH3CO 2)(CH3CO2)(C5H5N) 6][PF6]2·2H2O. The cubane and partial cubane dication have average Co ... Co distances of 2.818(8), 2.683(6) and 2.918(6), 2.767(5) A, respectively, and average Co - μ3-O distances of 1.86 and 1.91 A, respectively.
- Beattie, James K.,Hambley, Trevor W.,Klepetko, John A.,Masters, Anthony F.,Turner, Peter
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p. 1343 - 1354
(2008/10/09)
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- Catalyzed process for producing metal carboxylates for use as animal feed supplements
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A catalyzed process is disclosed for producing a polyvalent metal C2 -C3 carboxylate having the formula M(CH3 (CH2)x COO--)y, wherein M is the polyvalent metal cation that is manganese (Mn+2), cobalt (Co+2), or chromium (Cr+3), x is zero or 1 and y is an integer equal to the cationic charge of M. The polyvalent metal C2 -C3 carboxylate is prepared by admixing (i) a dry polyvalent metal compound that is an oxide, hydroxide or carbonate of Mn+2, Co+3 or Cr+3, (ii) an anhydrous C2 -C3 carboxylic acid, and (iii) a catalytic agent at a relative molar ratio of about 1:2-10:0.01-3 in the absence of an added solvent or other diluent to form a reaction mixture. The reaction mixture is heated to complete the reaction, remove the produced water and about 80 percent of the unreacted carboxylic acid. The product in residual carboxylic acid is solidified, ground and the product is recovered. The metal carboxylates can be used as biologically available and economical sources of trace metal ions for supplementation in animal diets.
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- Recovery of acetyl values from ethylidene diacetate
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Disclosed is a process for the recovery of acetyl values from an ethylidene diacetate stream obtained from an acetic anhydride production system. The process comprises hydrolyzing ethylidene diacetate in a liquid phase, hydrolysis zone containing a non-volatile, acidic catalyst and maintained under boiling conditions to obtain a mixture of acetaldehyde, acetic acid and water and then oxidizing the mixture in a liquid phase, oxidation zone containing a cobalt oxidation catalyst to obtain a mixture of acetic acid and water. The process optionally includes a means for reducing substantially the concentration of iodine in the EDA used in the process.
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- Characterization of the reaction of cobalt(II) acetate, dioxygen and acetic acid, and its significance in autoxidation reactions
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When cobalt(II) acetate is added to an oxygenated solution of acetic acid at reflux, a reaction occurs producing cobalt(II) acetate, carbon dioxide, carbon monoxide, methane, methyl acetate and water. Evidence is presented that this reaction is initiated by a trace amount of adventitious peroxide in acetic acid and is then is propagated via a free radical chain reaction. A balanced set of reactions is given which are consistent with the products observed. It is suggested that this is the initiation step in cobalt-catalyzed autoxidations in acetic acid. Of the first row metal acetates from calcium to zinc, only cobalt(II) acetate undergoes this reaction. It is shown that cobalt is, by far, the most active autoxidation catalyst toward p-toluic acid in acetic acid. The author concludes that the Co(OAc)2/O2/ HOAc reaction is one of the reasons for cobalt's unique character as an autoxidation catalyst in carboxylic solvents.
- Partenheimer
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- Photochemical ligand dissociation, electron transfer, and metal-metal bond cleavage of phosphine-substituted cobalt carbonyl complexes
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The major photochemical reactions of [Co(CO)3L2][Co(CO)4] are initiated by photolysis of the cation Co(CO)3L2+. Upon photolysis Co(CO)3L2+ loses a ligand, either CO or L (L = tributylphosphine), to give Co(CO)2L2+ and Co(CO)3L+ which will react with Co(CO)4- to give Co2(CO)6L2 and Co2(CO)7L, with excess L to give Co(CO)2L3+ and Co(CO)3L2+, and with H2 to give HCo(CO)2L2 and HCo(CO)3L, respectively. The neutral complex Co2(CO)6L2 is photostable in the absence of phosphine. With an excess of L it undergoes either photosubstitution to Co2(CO)5L3 and Co2(CO)4L4 or disproportionation to [Co(CO)2L3][Co(CO)4] (major) and [Co(CO)3L2][Co(CO)3L], depending on the nature of the solvent (hexane or methanol, respectively). Electron-transfer and radical reactions are responsible for the observed products.
- Mirbach, Marlis F.,Mirbach, Manfred J.,Wegman, Richard W.
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p. 900 - 903
(2008/10/08)
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- Making 1,2,4-butanetriol by hydroformylation of glycidol
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1,2,4-Butanetriol is produced by hydroformylation of a solution of glycidol and reduction of the hydroformylation reaction products.
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- The Solvation of Cobalt(II) and Zinc(II) Acetates in Dioxan-Hexane and Tetrahydrofuran-Hexane Mixtures
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The state of cobalt(II) and zinc(II) acetates in dioxan-hexane and tetrahydrofuran-hexane mixed solvents has been investigated by solubility and spectrophotometric methods at 298.15 K.It is shown that the acetates exist in dioxan and tetrahydrofuran as tetrahedral complexes with a solvation number of 2.The stability constants of these complexes have been calculated.
- Kazakova, I. M.,Golubchikov, O. A.,Berezin, B. D.
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p. 476 - 478
(2007/10/02)
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- State of Cobalt(II) Acetate in Binary Solvents Based on Acetic Acid
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Solubility and apectrophotometry have been used to investigate the state of cobalt acetate in binary solvents comprising acetic acid with small additions of ethyl acetate, aminoethanol, or ethylene glycol.Stability constants of the mixed solvated complexes have been calculated from the solubility data.
- Kazakova, I. M.,Golubchikov, O. A.,Berezin, B. D.,Ocheretovyi, A. S.
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- COORDINATION COMPOUNDS OF Co(II) WITH 2-METHYL- AND 1,2-DIZAMETHYLBENZIMIDAZOLE.
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The synthesis is described of new coordination compounds of Co(II) with 2-methylbenzimidazole and 1,2-dimethylbenzimidazole. Salts of cobalt(II) with organic acids (formic, acetic, propionic, butyric) were investigated. IR spectra, diffractograms, electronic spectra, and magnetic properties were investigated, on the basis of which conclusions were drawn concerning the structure of the materials.
- Slyusarenko,Artemenko,Lapina,Pokhodnya,Zakharenko
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