55881-15-7Relevant articles and documents
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
Beattie, James K.,Hambley, Trevor W.,Klepetko, John A.,Masters, Anthony F.,Turner, Peter
, p. 1343 - 1354 (1998)
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.
Factors affecting the selectivity of the oxidation of methyl p-toluate by cobalt(III)
Sumner Jr., Charles E.,Morrill, Kent A.,Howell, Jeff S.,Little, James
, p. 2190 - 2195 (2008)
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].
Synthesis and characterization of some trinuclear cobalt(II) thiocarboxylates
Baranwal,Gupta, Tarkeshwar
, p. 1855 - 1864 (2002)
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.
Co(II)-salen catalyzed stereoselective cyclopropanation of fluorinated styrenes
Tai, Serene,Maskrey, Taber S.,Nyalapatla, Prasanth R.,Wipf, Peter
, p. 1014 - 1027 (2019/11/14)
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.
The Role of Iodanyl Radicals as Critical Chain Carriers in Aerobic Hypervalent Iodine Chemistry
Hyun, Sung-Min,Yuan, Mingbin,Maity, Asim,Gutierrez, Osvaldo,Powers, David C.
supporting information, p. 2388 - 2404 (2019/09/12)
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.
The Kinetics of Growth of Metallo-supramolecular Polyelectrolytes in Solution
Munzert, Stefanie Martina,Stier, Simon P.,Schwarz, Guntram,Weissman, Haim,Rybtchinski, Boris,Kurth, Dirk G.
, p. 2898 - 2912 (2017/10/06)
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.
Kinetic stability of complexes of some d-metals with 3,3'- bis(dipyrrolylmethene) in the binary proton-donor solvent acetic acid-benzene
Antina,Guseva,V'yugin,Antina
, p. 1293 - 1297 (2013/01/14)
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
Structural, spectral and magnetic properties of carboxylato cobalt(II) complexes with heterocyclic N-donor ligands: Reconstruction of magnetic parameters from electronic spectra
Titis,Hudak,Kozisek,Krutosikova,Moncol',Tarabova,Boca
, p. 106 - 113 (2012/07/14)
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]
Kinetics and products of the catalytic oxidation of acetamidotoluenes with ozone in acetic acid
Galstyan,Bushuev,Sementsov
, p. 516 - 520 (2011/01/07)
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.
Synthesis and characterization of ternary carboxylato complexes of cobalt(II) with Schiff bases
Baranwal, Bairam Prasad,Singh, Atresh Kumar,Fatma, Talat,Gupta, Tarkeshwar
, p. 2006 - 2010 (2007/10/03)
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.
