1277-43-6Relevant academic research and scientific papers
Consequences of the protonation of the 19-electron anion [Co(η5-C5H5)(l,5-C8H 12)]-
Shaw, Michael J.,Eilers, James E.,Geiger, William E.
, p. 5349 - 5357 (2009)
The electrochemical and chemical reduction of CoCp(1,5-COD) (1, Cp = η5-C5H5; COD = cyclooctadiene) has been reinvestigated in THF. Whereas the initially formed monoanion 1- (E1/2 = -3.01 V vs Fc, Fc
Cobaltocenium acetylsalicylate: synthesis and circular dichroism study of interactions with DNA
Snegur,Kaverin,Babievsky
, p. 1787 - 1790 (2019)
Cobaltocenium acetylsalicylate was synthesized and characterized for the first time. The concentration dependences observed in its interaction with the double helix of DNA have been studied by circular dichroism. In these spectra, changes in the positions and decrease in the intensities of the curves in the positive and negative regions are observed when adding in increasing concentrations of cobaltocenium acetylsalicylate to calf thymus DNA. The observed changes in the effects of Cotton were interpreted as local changes in the conformation of the DNA double helix caused by the interaction of positively charged metallocenium cations with phosphate DNA fragments.
Neodymium and dysprosium diiodides in the synthesis of vanadocene and cobaltocene
Bochkarev,Burin
, p. 2179 - 2181 (2004)
The reaction of NdI2 or DyI2 with VCl3 and cyclopentadiene in THF at 65-70°C without isolation of the intermediates afforded vanadocene in 55 and 68% yields, respectively. An analogous reaction of DyI2 with CoCl
Fast electron transfer across semiconductor-molecule interfaces: GaAs/Co(Cp)2+/0
Meier, Andreas,Selmarten, Donald C.,Siemoneit, Kerstin,Smith, Barton B.,Nozik, Arthur J.
, p. 2122 - 2141 (1999)
The kinetics of majority electron transfer in the dark from n-GaAs electrodes to cobaltocenium (Co(Cp)2+) acceptors in acetonitrile has been studied in detail, both experimentally and theoretically. The experimental results were obtained from electrochemical impedance spectroscopy, quartz crystal microbalance (QCM and EQCM) studies, and current-potential characteristics. The theoretical work involved calculating the adsorption energy and molecular configuration of the cobaltocenium acceptors at the GaAs surface using high level density functional theory (B3LYP and variations thereof) as well as semiempirical methods. The QCM experiments showed that both Co(Cp)2+ and Co(Cp)20 are physisorbed at GaAs surfaces, with adsorption energies of about 0.2 and 0.4 eV, respectively. The theoretical results are consistent with these experimental results. They indicate that adsorption of the Co(Cp)2+/0 redox system occurs on GaAs, with Co(Cp)20 somewhat more strongly adsorbed than Co(Cp)2+; the Co(Cp)2+/0 molecules were found to adsorb with the cyclopentadienyl rings parallel to the GaAs surface. A model for the overall electron-transfer process was developed that incorporates Co(Cp)2+ adsorption. Analysis of the detailed impedance spectra over the range of 1 Hz to 600 kHz showed that the sequential electron-transfer steps in the model (i.e., electron transfer from the GaAs conduction band to adsorbed Co(Cp)2+, followed by electron transfer from the adsorbed Co(Cp)20 to free Co(Cp)2+ in solution) are very fast and that the observed overall rate of electron transfer is limited by the rate of thermionic emission from the GaAs bulk region to the surface. The implications of these results for the theory of electron transfer at semiconductor-liquid interfaces, and the associated controversies surrounding theory and various experimental results for GaAs-metallocenium systems, are discussed.
Synthesis and reactivity of ruthenium complexes with dibenzothiophene and hexahydrodibenzothiophene ligands: Models for catalytic hydrodesulfurization
Wang, Chia-Mei Jen,Angelici, Robert J.
, p. 1770 - 1777 (1990)
As models for the adsorption of dibenzothiophene (DBT) and hexahydrodibenzothiophene (HHDBT) on hydrodesulfurization (HDS) catalysts, the complexes CpRu(DBT)+, CpRu(HHDBT)+, and [(CpRu)2(DBT)]2+ were prepared. I
The Orbital-Overlap Factor in Electron Transfer: Sensitivity of Homogeneous Self-Exchange Kinetics for Some Metallocenes to Electronic Structure
Nielson, Roger M.,Golovin, M. Neal,McManis, George E.,Weaver, Michael J.
, p. 1745 - 1749 (1988)
Rate constants, khex, for the electron self-exchange of cobaltocenium-cobaltocene, Cp2Co+/0, and for the decamethyl derivative, (Cp-Me5)2Co+/0, obtained by using the NMR line-broadening technique in acetonitrile and dimethyl sulfoxide are compared with corresponding data for the ferrocene couples Cp2Fe+/0 and (Cp-Me5)2Fe+/0 and for bis(benzene)chromium(I)/(0).The rate constants in a given solvent display a marked sensitivity to the reactant structure, the khex values being about tenfold larger for Cp2Co+/0 relative to Cp2Fe+/0; decamethyl substitution yields tenfold increases in khex for both these couples.A relationship is established between these ca. 100-fold rate variations and the nature of the donor and acceptor orbitals.In particular, the markedly slower self-exchange kinetics observed for Cp2Fe+/0 relative to Cp2Co+/0 are consistent with the much greater ligand-delocalized character of the 4elg orbital involved in the latter electron transfer as compared with the 4e2 or 8alg orbital for the former reaction.The same argument is likely to account for the similar relative rates for (Cp-Me5)2Fe+/0 versus (Cp-Me5)2Co+/0.These rate differences are very unlikely to be due to variations in nuclear reorganization factors since the molecular structures of these couples are virtually identical, and they feature only small differences (ca. 0.3 kcal mol-1) in the inner-shell barriers.The results therefore provide unusually clear evidence for the influence of donor-acceptor electronic coupling in outer-sphere redox reactivity.
In situ measurement of the conductivity of polypyrrole and poly[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium]+ as a function of potential by mediated voltammetry. Redox conduction or electronic conduction?
Mao, Huanyu,Pickup, Peter G.
, p. 1776 - 1782 (1990)
The electronic conductivity of polypyrrole and poly[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium]+ (poly-MPMP+) films has been investigated by rotating disk voltammetry. In this in situ measurement, a solution redox species such as cobaltocene, ferrocene, or Cr(2,2′-bipyridine)3+ serves as an electron source at the polymer/solution interface, while electrons are removed at the polymer/electrode interface. The oxidation state of the polymer is controlled by the potential applied to the electrode. The experimental data have been interpreted in terms of both electronic and redox conduction models. A comparison of the results from these two models reveals that the electronic conductivity and the electron diffusion coefficient are related by the Nernst-Einstein equation. It is concluded that electron transport occurs by a hopping mechanism and that the two models are equivalent descriptions of this process in the pyrrole-based polymers. The electronic conductivity of both polymers initially increases linearly with the degree of oxidation of the polymer backbone (concentration of oxidized sites). The conductivity of polypyrrole rises exponentially from 10-8 to 5 × 10-6 Ω-1 cm-1 over the potential range of -0.7 to -0.4 V, while the electron diffusion coefficient remains constant at ca. 10-7 cm2 s-1. At higher potentials the conductivity is too high to be accurately determined by rotating disk voltammetry. The conductivity of poly-MPMP+ increases from ca. 10-9 Ω-1 cm-1 at +0.35 V to ca. 10-4 Ω-1 cm-1 at +1.0 V.
FLASH-VACUUM PYROLYSIS OF η5-CYCLOPENTADIENYLDICARBONYLCOBALT. FORMATION OF COBALTOCENE
Fiaud, Jean-Claude,Chauvin, Remi,Bloch, Robert
, p. C32 - C34 (1986)
Flash-vacuum pyrolysis (350 deg C, 0.1 Torr) of cyclopentadienyldicarbonylcobalt afforded cobaltocene (85percent yield) at the end of the pyrolysis tube.This compound is formed in a bimolecular reaction in the hot zone of tube between species from which CO ligands have been lost.
A process for preparing [...]
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Paragraph 0029-0056, (2019/03/29)
The invention provides a preparation technology of cobaltocene. The preparation technology comprises the following steps: (1) reacting cobalt dichloride with a metal compound containing alkyloxy in an oxygen-free first alcoholic solvent to obtain a cobalt compound containing alkyloxy; (2) reacting the alkyloxy-containing cobalt compound obtained in the step (1) with a cyclopentadiene monomer in a second alcoholic solvent to obtain a mixed solution containing cobaltocene, and carrying out distillation to remove the solvent to obtain a coarse product of cobaltocene; (3) dissolving the cobaltocene coarse product obtained in the step (2) into a non-proton solvent, filtering, adding an ether solvent into the condensed filtrate, and carrying out recrystallization to obtain cobaltocene solids. The raw materials used in the provided preparation technology all have a wide source and low price. The reagents, which need strict reaction conditions, such as metal sodium, amino sodium, and the like, are not used in the provided preparation technology. Moreover, the reaction conditions are mild, the operation is convenient and safe, the production cost is low, thus the preparation technology is very suitable for industrial production, and the cobaltocene product is high-purity solid crystals.
Direct synthesis of an anionic 13-vertex closo-cobaltacarborane cluster
Maier, Thomas M.,Coburger, Peter,Van Leest, Nicolaas P.,Hey-Hawkins, Evamarie,Wolf, Robert
supporting information, p. 15772 - 15777 (2019/11/11)
Reaction of 1,2-bis(diphenylphosphino)-ortho-carborane (L) with [K(thf){(MesBIAN)Co(η4-cod)}] (1, MesBIAN = bis(mesityliminoace-naphthene)diimine, cod = 1,5-cyclooctadiene) affords an anionic 13-vertex closo-cobaltacarborane cluster (2) in one step. The mechanism of this transformation has been studied by experimental and quantum chemical techniques, which suggest that a series of outer-sphere electron transfer and isomerisation processes occurs. This work shows that low-valent metalate anions are promising reagents for the synthesis of anionic metallacarborane clusters.
