Bivalent Cobalt Research Articles

Synthesis and characterization of bivalent metal complexes of a tetradentate N 6 macrocyclic ligand

Bivalent cobalt, nickel and copper salts react in situ with 2,6-diacetylpyridine and 1,2-diaminobenzene to form complexes containing a 18-membered N 6 tetradentate macrocyclic ligand. The complexes were characterized as distorted octahedral of the type: [M(TML)X 2; where M = Co II, Ni II or Cu II; X = Cl, Br, NO 3 or NCS; TML = tetradentate macrocyclic ligand. The ligand coordinates through all the six nitrogen atoms. The molar conductance measured in DMF show that these chelates are 1:2 electrolytes. The test for anions are positive directly without decomposing the chelates, showing their presence outside the coordination sphere. The magnetic, electronic, IR and far-IR spectral studies are also discussed.

Binuclear chromium(III), manganese(III), iron(III) and cobalt(III) complexes bridged by diaminopyridine

Trivalent chromium, manganese, iron and bivalent cobalt salts react with 2,6-diaminopyridine and acetylacetone to give complexes of the type [M(C 15H 17N 3O 2)X] [where X  Cl, Br, NO 3 or NCS for M = chromium(III) and iron(III); X  Cl, Br, OAc or NCS for manganese(III)]. Conductance measurements show the complexes to be non-electrolytes. Molecular weights determined cryoscopically suggest the dimeric nature of these complexes. Magnetic measurements above 85 K reveal the presence of some antiferromagnetic exchange via 2,6-diaminopyridine moieties. The complexes are dimeric five-coordinate square-pyramidal with 2,6-diaminopyridine residues acting as bridges. The electronic spectra are interpreted in terms of the normalized spherical harmonic Hamiltonian theory and the DT/DQ values which indicate that chromium complexes are slightly distorted, whereas those of manganese are severely distorted.

1:1 Metal Complexes of Bivalent Cobalt, Nickel, Copper, Zink, and Cadmium with the Tripodal Ligand tris[2‐(dimethylamino)ethyl]amine: Their stabilities and the X‐ray crystal structure of its copper(II) complex sulfate

AbstractThe complex formation by Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ with tris[2‐(dimethylamino)ethyl]amine (N(CH2CH2NMe2)3, Me6tren) was investigated at 25° and at an ionic strength of 1, using VIS spectroscopy and potentiometric measurements. The stability constants of these complexes are compared with those of tris(2‐aminoethyl)amine (N(CH2CH2NH2)3, tren), obtained under the same conditions. The values of the constants for Me6tren are much lower than those for tren, due to the bulky Me substituents. The values of the constants can be correlated with the ability of the individual metal ions to adopt coordination number 5. This appears to be easier for Cu2+ and Co2+ than for Cd2+ and Zn2+ and is very difficult for Ni2+. The 1:1 complexes [ML(H2O)]2+ are monoprotonic acids whose pKs values are similar or lower than those of the corresponding aquametal ions. The X‐ray crystal structure of the copper(II) complex [Cu(SO4)(Me6tren)] · 8H2O reveals pentacoordination at the central ion. The UV/VIS spectra of the aqueous solutions of the Co2+, Ni2+, and Cu2+ 1:1 complexes confirm that the same coordination number is present also in these complexes.

Study on the properties of iron–cobalt alumina supported catalyst for ammonia

AbstractThe addition of Co to Fe/Al2O3 increases the catalytic activity in NH3 synthesis. The maximum effect is observed for 20% by weight of Co in the metallic phase. Bivalent cobalt atoms replace bivalent iron atoms (a similar ionic radius) in the crystal lattice. This process changes the reducibility of the samples. The Fe‐Co compound and its formation results in the fairly high temperature of reduction (873 K) which is needed to prepare the most active catalyst. Changing the reactor atmosphere from reducing to inert causes the disappearance of free iron (escape of Fe to the crystal lattice of support with formation of a new compound with a spinel character). This is the effect of the iron‐hydrogen interaction. The formation of an intermetallic iron‐cobalt compound is crucial to the catalyst activity. This might be due to the surface restructuring by exposing the most active iron surface, Fe(111). The potassium addition in the form of KOH causes an increase in the catalytic activity. The increase is not as high as for a ‘super basic’ Fe‐Co magnesium hydroxide carbonate supported catalyst studied earlier. A part of the potassium hydroxide is used to neutralize the acid sites on the surface of alumina.

IR, PMR and TG Studies on Substituted 1,3,5-Triphenylformazans Complexes with Bivalent Cobalt, Nickel, Copper and Zinc

IR, PMR and TG Studies on Substituted 1,3,5-Triphenylformazans Complexes with Bivalent Cobalt, Nickel, Copper and Zinc

XANES study of two bivalent cobalt polymers

AbstractXANES (x‐ray absorption near edge structure) in the vicinity of the K absorption edge of cobalt has been studied for two bivalent cobalt polymers, viz. cobalt(II) azelaic acid bis(phenylhydrazide) and cobalt(II) sebacic acid bis(2,4‐dinitrophenylhydrazide), using a bent crystal x‐ray spectrograph of the Cauchois type. This study helped in the determination of the average bond lengths in the two compounds. The study of the chemical shifts and the edge widths throws some light on the relative covalency in these complexes.

Formation Constants of N-Benzenesulphonyl·L-(—)-histidine and Related Ligands with Bivalent Cobalt, Nickel, Copper, Zinc and Cadmium

Formation Constants of N-Benzenesulphonyl·L-(—)-histidine and Related Ligands with Bivalent Cobalt, Nickel, Copper, Zinc and Cadmium

ChemInform Abstract: SYNTHESIS AND MAGNETIC PROPERTIES OF BINUCLEAR COMPLEXES OF UNIDENTATE LIGANDS WITH ACETYLACETONATES OF BIVALENT MANGANESE, COBALT, AND NICKEL

Chemischer InformationsdienstVolume 13, Issue 20 Organoelement Compounds ChemInform Abstract: SYNTHESIS AND MAGNETIC PROPERTIES OF BINUCLEAR COMPLEXES OF UNIDENTATE LIGANDS WITH ACETYLACETONATES OF BIVALENT MANGANESE, COBALT, AND NICKEL M. A. LAFFEY, M. A. LAFFEYSearch for more papers by this authorP. THORNTON, P. THORNTONSearch for more papers by this author M. A. LAFFEY, M. A. LAFFEYSearch for more papers by this authorP. THORNTON, P. THORNTONSearch for more papers by this author First published: May 18, 1982 https://doi.org/10.1002/chin.198220294AboutPDF 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. Volume13, Issue20May 18, 1982 RelatedInformation

Studies on the metal-amide bond. XIV. The coordination chemistry of N-methyl-N,N′-bis(2′-pyridinecarboxamide)-1,2-ethane; a potentially tetradentate ligand containing both secondary and tertiary amide groups

The isolation and characterization of a number of transition metal complexes of the ligand N-methyl-N,N′-bis(2′-pyridinecarboxamide)-1,2-ethane, bpen-MeH, is described. Representive non-deprotonated 1:1 complexes of bivalent cobalt, nickel copper and zinc show the ligand to act as a bis-bidentate, forming five- or six-coordinate polymeric complexes involving coordination through pyridyl nitrogen and amide oxygen atoms. The complexes Cu 2(bpenMeH)Cl 4 and Ni 2(bpenMeH) 3(ClO 4) 4·7.5H 2O also demostrate this mode of bonding by the ligand. One complex alone of bivalent palladium. was obtained in which coordination of the deprotonated secondary-amide nitrogen atom occurs. Coordination of the tertiary-amide nitrogen atom is not observed for any of the complexes.

BIVALENT COBALT COMPLEXES WITH 1-(2-PYRIDYLAZO)-2-NAPHTHOL (β-PAN) AND ANALOGOUS LIGANDS

Abstract Bivalent cobalt complexes with the title ligands were synthesized and isolated. They were characterized by absorption spectra and magnetic moments. The Co (II) complexes were found to be oxidized to the Co (III) complexes in DMSO in the presence of Cu(II) ions.

Complexes of some bivalent cobalt, nickel, copper, zinc, cadmium and monovalent silver salts with 4,4?-BipyridylN,N?-dioxide

Coordination compounds have been prepared from 4,4′-hipyridylN,N′-dioxide (4,4′-BipyO2) and some hivalent metal halides, nitrates and thiocyanates as well as silver(1) nitrate.viz., Co(4.4′-BipyO2)2Cl2, Co(4.4′-BipyO2)Br2, Co(4,4′-Bi-pyO2)(NO3)2. Co(4,4′-BipyO2)2(NCS)2. Ni(4.4′-BipyO2)2Cl2. Ni(4,4′-BipyO2)(NO3)2, Ni2(4.4′-BipyO2)3(NSC)4. Cu(4,4′-BipyO2)(NO3)2. Zn(4,4′-BipyO2(NO3)2, Zn,(4.4′-BipyO2)3-(NCS)4. Cd(4.4′-BipyO2)(NO3)2, Cd(4.4′-BipyO2)2(NCS)2 and Ag(4,4′-BipyO2)(NO3). The products were characterized by magnetic susceptibility. electronic and i.r. spectral measurements down to 200 cm−1. Tentative stereochemistries for the complexes isolated in the solid state are proposed. The ligand field parameters 111 Dy. B. j3. )., and calculated for the cobalt. nickel and copper complexes are consistent with these stereochemistries.

Reaction of Bis[1-(2-pyridylazo)-2-naphtholato]cobalt(III) Chloride, [CoIII(pan)2]Cl, with Hyperoxide in Dimethyl Sulfoxide

Abstract The complex [CoIII(pan)2]+ was found to react in DMSO with hyperoxide, O2−, to give a bivalent cobalt complex [CoII(pan)2]0. The oxidation of [CoII(pan)2]0 to [CoIII(pan)2]+ by oxygen did not proceed in DMSO in the absence of water and/or H+. The standardization of O2− in DMSO were also described.

ECE Mechanism as a Tool for the Investigation of Unstable Metal Complexes. II. Current-Potential Characteristics for the Reversible Deposition of an Insoluble Species: Case of Electrochemical Reduction of trans-Dibromobis(ethylenediamine)cobalt(III) Complexes

Abstract Theoretical relations were derived for the ECE mechanism involving the reversible deposition of an insoluble species at constant potential (potentiostatic method). Assuming that the activity of deposit becomes equal to unity immediately after the beginning of electrolysis, current-potential relations were obtained for the case in which the first electron transfer step is irreversible and the second one, reversible. The method was used to study the acid hydrolysis of bivalent cobalt complex in the reduction of trans-dibromobis(ethylenediamine)cobalt(III) complex. The measurement made at 5 °C in 0.1 M acetate buffer solutions (pH 4.8) gave 0.4 s−1 for the acid hydrolysis of trans-dibromobis(ethylenediamine)cobalt(II) which was produced by the reduction of cobalt(III) complex.

Co IIIS 4P 2] + — A new chromophore: Synthesis, characterisation and electrochemistry of bis(diethyldithiocarbamato) {1,2-bis(diphenylphosphino)ethane}cobalt(III) chloride and tetraphenylborate

The cobalt(III) complexes, bis(diethyldithiocarbamato) {1,2-bis(diphenylphosphino)ethane}cobalt(III) chloride and tetraphenylborate are synthesised starting from bivalent cobalt and characterised by IR, Raman, NMR and UV-Vis spectra.

Metal complexes of 1,10-phenanthroline derivatives. XI. Complexes of 1,10-Phenanthroline-2,9-di(carbaldehyde phenylhydrazone)

1,10-Phenanthroline-2,9-dicarbaldehyde has been prepared by oxidation of 2,9-dimethyl-1,10-phenanthroline with selenium dioxide. The value of the dialdehyde in the synthesis of open-chain multidentate chelating agents has been examined and the function of the di(phenylhydrazone) derivative is described. Steric constraints within the molecule render quadridentate function difficult and a distinct tendency to tridentate coordination is observed. Complexes of the dihydrazone with bivalent iron, cobalt, nickel and copper are described.

Synergism of Co(II) napthenate and sodium hydroxide in catalytic decomposition of cyclohexylhydroperoxide

Sodium hydroxide and bivalent cobalt naphthenate are catalysts in the decomposition of cyclohexyl hydroperoxide in cyclohexane and in mixtures have marked synergistic action (decomposition rate constant 0.32 sec/sup -1/).

Derivatographic Studies on Transition Metal Complexes. XX. Thermal Electron Transfer Reactions of Cobalt(III) Complexes Containing Phenylbiguanide in the Solid Phase

Abstract The following six cobalt(III) complexes containing phenylbiguanide were prepared and the thermal reactions were followed both isothermally and non-isothermally (derivatographically) in the solid phase: trans-[Co(A)2(phbgH)2]X3·n2O, where A denotes volatile ligands such as NH3, CH3NH2 or C5H5N; phbgH denotes 1-phenylbiguanide, X chloride or bromide ion; and n is 2 or 3. From the electronic, IR and far-IR spectra and magnetic susceptibilities of these complexes before and after heating, the products obtained by evolving volatile ligands were found to be uniform bivalent cobalt complexes without rupture of the bonds of phbgH to cobalt in spite of the reduction of central cobalt(III) ion, except for the complexes containing ammonia. The reaction seems to be caused by the electron transfer from the coordinated phbgH to cobalt, not from the outer-sphere anions.

Some complexes of s-triazine with cobalt(II) halides

The isolation of eight new complexes of bivalent cobalt with s-triazine of general formula CoX 2(trz) n(H 2O)m(where X = Cl, n= 1, m = 1 or 3; n= 2, m = 1; X = Br, n = 1, m = 0; n = 2, m = 0 or 2; X = I, n = 2, m = 0; X = NCS, n = 4, m = 1) is reported. The proposed four- and six-coordinate stereochemistries of these products are assigned after consideration of microanalyses, visible absorption spectra and magnetic moment data. In the main the complexes are stable only in the solid state below room temperature and in the absence of moisture. There is some evidence for a strong interaction between water and s-triazine in the Cl and NCS compounds.

Accumulation of cobalt during embryonic development of rainbow trout ( Salmo gairdneri Rich.)

Studies on the accumulation of cobalt by fish eggs are described. γ-Energy measurement of 57Co and atomic absorption with the flameless technique were used for the detection of the cobalt. The cobalt level of the eggs was found to be directly proportional to the cobalt content of the aquatic medium, and its uptake decreased with increasing calcium ion concentration in the water. The accumulation of bivalent cobalt ions was found to take place on the surface of the eggs, where they are reversibly bound by the binding force of chorion-mucopolysaccharide. The present study did not show any increase in cobalt content within the larvae that hatched from the eggs.

Liquid-phase oxidation of tetralin in the presence of heterogeneous catalysts

A STUDY Of heterogeneous catalysts in liquid-phase oxidation of hydrocarbons has recently at tracted increasing attention [1-3]. This interest is due to special features of the effect of the heterogeneous surface on the process as a whole and to a somewhat (in many cases) different distribution of reaction products. Typical heterogeneous catalysts of gaseous oxidation of hydrocarbons--transition metal oxides (IV and V periods) [4, 5]--were examined in most detail. Two points of view are now dealt with in the literature which are based on these investigations and concern the role of heterogeneous catalysts in liquidphase oxidation. According to the first, heterogeneous catalysts only initiate the process [2, 6]. Oi1 the other hand, it was found in many studies that in addition to the initiating effect, heterogeneous catalysts have a considerable influence on the distribution of reaction products [1, 7, 8]. This study deals with liquid-phase oxidation of tetralin in the presence of heterogeneous systems representing bivalent cobalt ions applied on zeolites, activated charcoal and silica gel. Cobalt oxide Co304 was also examined. Results obtained by oxidation of tetralin in heterogeneous catalysts were compared with results of non-catalytic oxidation and oxidation in the presence of cobalt stearate, a homogeneous catalyst.