Hydrogenation catalysts formation in the system AlEt3-Co(acac)2,3

Effect of Electron Donors on the Radical Polymerization of Vinyl Acetate Mediated by [Co(acac)2]: Degenerative Transfer versus Reversible Homolytic Cleavage of an Organocobalt(III) Complex

“…To the best of our knowledge, no EPR studies of [CoA C H T U N G T R E N N U N G (acac) 2 (ED) 2 ] complexes have been reported, and solutions of [CoA C H T U N G T R E N N U N G (acac) 2 ] itself in toluene are described as EPR-silent. [42] We therefore turned to NMR investigations. Indeed, the rapid relaxation of the electron-spin magnetization (conditions leading to very broad EPR resonances) favor the observation of relatively sharp (though paramagnetically shifted) NMR resonances.…”

Spin Ground State and Magnetic Properties of Cobalt(II): Relativistic DFT Calculations Guided by EPR Measurements of Bis(2,4-acetylacetonate)cobalt(II)-Based Complexes

“…7 However, thorough examination of the mechanism of the Co(acac) 2 -mediated polymerization is still a challenging issue, i.a., due to the difficulties in determination of the lowest-energy spin state and preferred geometry of the key Co(acac) 2 complex under the reaction conditions. 9 One of the characteristic features of divalent cobalt implicated by its 3d 7 electronic configuration is the presence of two spin states, a doublet 2 Co II (S = 1/2) and a quartet 4 Co II (S = 3/2) one, depending on the chemical environment. In principle, they can be distinguished with the help of electron paramagnetic resonance (EPR) spectroscopy.…”

Formation of the cobalt hydrogenation catalysts at the action of lithium aluminum hydride and lithium tri(tert-butoxy)aluminohydride and their properties

“…To date, experimentally has been shown that the coreagents in the Ziegler type systems are involved in the formation of hydride or an organic derivative of the transition metal, reduction of the transition metal compound, most often to the metal in the zero oxidation state, formation of adducts with the reduced form of the transition metal of the type of acid-base interaction, and stabilization of nanoparticles [6][7][8]. However, some aspects of this problem have not yet been substantiated experimentally.…”

“…These results have generated the need to study the cobalt-containing catalytic systems, formed by using LiAlH 4 and its alkoxy derivative LiAlH(t-BuO) 3 Red:Co two features: a high activity in the hydrogenation of alkenes and arenes [3,7] and a possibility of carrying out the reactions of conjugated hydrogenation of alkenes and arenes in the presence of the systems modified with trialkylphosphines [12]. A research of the cobalt-containing catalytic systems will allow establishing general patterns and characteristics of the catalysts formed at the action of LiAlH 4 and its alkoxyhydride derivatives on the cobalt compounds.…”

“…The IR spectra of Co(acac) 2 -nLiAlH 4 (n = 2) recorded 10 min after the start of the reaction indicated lower intensity of the absorption bands at 1586 and 1520 cm -1 of the mixed stretching vibrations [ν(C=O)+ν(C = C)] of the acac ligands in O,O-chelate form of Co(acac) 2 [7] and the appearance of new poorly resolved absorption bands at 1607 and 1515 cm -1 , characteristic of stretching [ν(C=O) + ν(C=C)] vibrations of the acac ligand in Li(acac), indicating the transfer of the acac ligands from cobalt to lithium. For n = 4, in the IR spectrum in the region of 1500-1700 cm -1 only the absorption bands of acac ligand in Li(acac) were registered.…”