Cobalt Carboxylate Research Articles

Oxidation of alkanes by cobalt(II) salts of weakly coordinating anions

Catalysts which effect the selective oxidation of alkanes under mild reaction conditions are highly desired. Commercial processes exist which involve the oxidation of alkanes by O{sub 2} with cobalt carboxylate catalysts. Elevated temperatures and pressures are required, and the metal ion function is to decompose hydroperoxides formed in a radical-chain process. The authors have demonstrated that a weakly solvated cobalt-acetonitrile complex (Co(NCCH{sub 3}){sub 4})(PF{sub 6}){sub 2}, with a weakly coordinating anion catalyzes the air oxidation of alkanes under mild conditions (75C and 3 atm). Cyclohexane and adamantane are converted to the corresponding alcohol and ketone products. The commercial catalyst for cyclohexane oxidation does not function under these milder conditions. Experiments indicate a mechanism in which the metal ion functions both as an initiator and as a hydroperoxide decomposition catalyst.

Magnetic and spectroscopic study of some binuclear and trinuclear cobalt(II) carboxylate complexes

Binuclear [Co2(RCO2)4L2] and trinuclear [Co3(RCO2)6L2] cobalt(II) carboxylate complexes have been prepared (R = unsaturated alkyl, L = sterically hindered amine). The roles of electronic and steric effects on the formation of oligonuclear cobalt(II) carboxylates are discussed. The temperature dependence of their antiferromagnetism shows variations as R and L are altered.

Cobalt(II) complexes of creatinine

Cobalt(II) complexes of creatinine [Co(creat)2X2] (X = Cl, Br, I or NCS) and [Co(creat)2X2(H2O)2] (X = HCO2, HOCH2CO2 or CNCH2CO2) have been prepared. Their i.r. spectra show an increase in ν(NH) of the cyclic secondary amine group, compared to free ligand (3300 cm−1), indicating that cyclic nitrogen is involved in coordination. The thiocyanate group coordinates through nitrogen and carboxylates coordinate as univalent unidentate ligands. The electronic spectra and magnetic moments suggest a d7 configuration for cobalt: a tetrahedral geometry (4.4 B.M.) for halide and thiocyanate complexes, and an octahedral geometry (5.0 B.M.) for the carboxylate complexes. On heating, the ligand moiety is lost and the respective cobalt halide or cobalt carboxylate is formed, which is converted finally into Co3O4. There is a correlation between the high intensity electronic transitions and the polarographic half-wave potentials.

Superexchange in copper acetates

It was demonstrated in the preceding papers that the antiferromagnetic exchange coupling in a binuclear cobalt carboxylate is dominated by a superexchange mechanism via the carboxylate n bonds. In the present paper it is argued th at a similar process can account for all ground state properties of the structurally analogous, copper acetate molecule. The magnitudes, temperature-dependences and orientations of the principal magnetic susceptibilities can all be reproduced within this superexchange model. The g-values and zero-field splitting, previously considered to demonstrate the presence of a weak8bond between the copper atoms, have been shown to furnish no proof whatever of any particular coupling mechanism, provided there is an(x2 - y2 ground state for the copper atoms. The superexchange mechanism proposed is made possible essentially not via spin-orbit mixing of {xy) and (x2y2)— states but via configurational mixing of such functions caused by the close proximity of the second metal atom.

Magnetic properties of dimeric cobalt(II) carboxylates

Abstract The magnetic susceptibilities of two dimeric Co(II) carboxylates were measured in the range 1.6 to 300 °K. The compounds studied have similar structures to copper acetate monohydrate. The experimental data are treated in terms of various theoretical models. The results obtained are discussed.

ChemInform Abstract: MONONUCLEAR AND POLYNUCLEAR COMPLEXES OF COBALT(II) CARBOXYLATES WITH PYRIDINE AND OTHER HETEROCYCLIC BASES

AbstractDibenzoatokobalt reagiert in Äthanol mit Pyridinen zu den Komplexen (I) bzw. (II) und mit Chinolin abhängig vom Molverhältnis zu den Verbindungen (IIIa) bzw. (Va).

Mononuclear and polynuclear complexes of cobalt(II) carboxylates with pyridine and other heterocyclic bases

Adducts of cobalt(II) carboxylates with pyridine and related ligands have been prepared, their electronic spectra assigned, and their magnetic properties investigated. The complex [Co(py)2(O2CPh)2](py = pyridine) behaves as a six-co-ordinate species whose electronic spectrum shows retragonal splitting; [Co(2-Mepy)(O2CPh)2] has the properties of a trigonal-bipyramidal five-co-ordinate high-spin complex. The green complexes [Co2(quin)2-(O2CR)4](R = Ph or C6H4NO2-2; quin = quinoline) are antiferromagnetic binuclear species with square-pyramidal five-co-ordination. A slate-blue form of [Co(quin)(O2CC6H4NO2-2)2] behaves as a slightly antiferro-magnetic polymer. The complexes [Co3(quin)2(O2CR)6](R = Ph or C6H4NO2-2) contain a linear array of two trigonal-bipyramidal and one octahedral cobalt atoms and are not appreciably antiferromagnetic.

ChemInform Abstract: MASS SPECTRA OF TETRACOBALT(II) AND TETRAZINE(II)MY4‐OXO‐HEXA‐MY‐CARBOXYLATES (BASIC COBALT AND ZINC CARBOXYLATES)

Chemischer InformationsdienstVolume 6, Issue 35 Organoelement Compounds ChemInform Abstract: MASS SPECTRA OF TETRACOBALT(II) AND TETRAZINE(II)MY4-OXO-HEXA-MY-CARBOXYLATES (BASIC COBALT AND ZINC CARBOXYLATES) J. CHARALAMBOUS, J. CHARALAMBOUSSearch for more papers by this authorR. G. COPPERTHWAITE, R. G. COPPERTHWAITESearch for more papers by this authorS. W. JEFFS, S. W. JEFFSSearch for more papers by this authorD. E. SHAW, D. E. SHAWSearch for more papers by this author J. CHARALAMBOUS, J. CHARALAMBOUSSearch for more papers by this authorR. G. COPPERTHWAITE, R. G. COPPERTHWAITESearch for more papers by this authorS. W. JEFFS, S. W. JEFFSSearch for more papers by this authorD. E. SHAW, D. E. SHAWSearch for more papers by this author First published: September 2, 1975 https://doi.org/10.1002/chin.197535307AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue35September 2, 1975 RelatedInformation

Preparation, X-ray crystal structure, and magnetic properties of a trinuclear cobalt(II) carboxylate

The trinuclear complex [Co3(quin)2(PhCO2)6] is produced by the slow reaction of quinoline with ethanolic cobalt(II) benzoate; its molecular structure, determined by X-ray methods, consists of a linear array of cobalt atoms bridged by benzoate groups, but the compound is only very weakly antiferromagnetic.

Preparation, crystal structure, and magnetic properties of a binuclear cobalt(II) carboxylate

The reaction of quinoline with ethanolic cobalt(II) benzoate produces the dimeric complex Co2(quin)2(C6H5CO2)4, whose molecular structure, determined by X-ray methods, shows a long cobalt-cobalt distance of 2·83 A, consistent with the compound's weak anti-ferromagnetism.

Room temperature curing of unsaturated polyesters with cobalt (II) complexes

AbstractCobalt promoters presently used in the polyester processing industry suffer from many shortcomings ranging from shelf instability to strong discoloration of the resins and relatively poor activity. This paper describes the various performance improvements obtainable with coordination complexes of cobalt which can be used as polymerization accelerators in presence of organic peroxide initiators. These complexes appear to present significant advantages over the conventional cobalt carboxylates. Catalytic activity up to ten times that of cobalt soap was recorded with some complexes in various resin systems, without deleterious effects on physical properties. As gel‐cure modifiers, the compounds evaluated seem to increase the long term shelf stability of pre‐promoted resins while reducing the discoloration and air inhibition during the curing process of polyester thin films.