Showing papers on "Cobalt published in 1973"

18-Tungstotetracobalto(II)diphosphate and related anions: a novel structural class of heteropolyanions

Abstract: The P2Co4(H2O)2W18O6810– anion contains four edge-linked coIIO6 octahedra with coplanar cobalt atoms, in addition to two fragments of the Keggin structure.

Heavy metal toxicities: levels of nickel, cobalt and chromium in the soil and plants associated with visual symptoms and variation in growth of an oat crop

Abstract: A study was made of toxicity in a field crop of oats on a soil developed in an area where ultrabasic rocks occur. An area selected for sampling showed a range of toxicity from the border where plants were normal to the centre where plants were most affected. The total nickel, cobalt, and chromium contents of the soil increased to high levels at the centre of the area. The concentration of the elements in soil solutions extracted with a centrfuge from soils at field capacity were in the order nickel > cobalt > chromium, the order in which they are found in natural waters. In the soil solutions nickel ranged from 0.13 to 3.25 p.p.m., cobalt from 0.03 to 0.14p.p.m., and chromium from 0.01 to 0.02p.p.m. The concentrations found in the soil solutions were compared with concentrations known to induce toxicities in oats grown in frequently renewed solution cultures. These comparisons indicated that the nickel ranged up to levels which were definitely toxic. At its highest level cobalt was present at less than one-tenth of the level needed to induce toxicity, while chromium was present at only one-hundredth of the minimum level for toxicity. Analyses of the toys of plants from the centre of the area indicated values of chromium which would be considered toxic, but because of the very low concentrations of chromium in the soil solutions it was considered more likely that the chromium detected was in soil material which the acid detergent washing procedure failed to remove. Evidence presented indicates the particular importance of contamination in the case of chromium. Nickel was present in much higher quantities at toxic levels. Cobalt was below toxic levels. The symptoms observed in the field and symptoms induced by the application of nickel to oats in pot cultures are described. A feature of these symptoms was a regular succession of chlorotic bands. The evidence suggested that the banding pattern, which is best developed in clear weather, relates to the changing conditions which influence the actively growing tissue as the leaf is emerging. The symptom provided us with a means of identifying nickel toxicity in the field. Degrees of toxicity were related to levels of elements in soil extracts and in the plants.

Connectivity patterns of crayfish giant interneurons: visualization of synaptic regions with cobalt dye.

Abstract: Intracellular injection of cobalt dye was used to visualize electrical synapses between two pairs of central giant interneurons and giant motoneurons in the crayfish central nervous system. A pair of giant motoneurons in each ganglion contacts the interneurons, but not all contact points are functional synapses. Cobalt dye reveals numerous fine projections that are present at synaptic contact points and absent at nonsynaptic contacts; intracellular recording confirms this correlation. The different connectivity patterns of the two pairs of interneurons are consistent with the different behavior patterns which they evoke.

Organocobalt complexes. Part I. Arene complexes derived from dodecacarbonyltetracobalt

Abstract: A series of tetranuclear arenecobalt carbonyls, ArHCo4(CO)9, are formed by treating hexacarbonylacetylenedicobalt complexes, (R1C2R2)Co2(CO)6, with arenes in the presence of norbornene derivatives, or from the cobalt carbonyls Co4(CO)12 and Co2(CO)8 by direct reaction with arenes. Stable complexes are obtained from alkyl- and alkoxy-benzenes, but not from halogeno- or acyl derivatives. The spectroscopic properties of the new complexes are reported.

The cobalt-rich regions of the samarium-cobalt and gadolinium-cobalt phase diagrams

Abstract: The boundaries of the homogeneity regions of the phases SmCo 5 , GdCo 5 and Gd 2 Co 17 have been determined by microscopic investigation. At elevated temperatures the homogeneity region of the phases SmCo 5 and GdCo 5 extends to the Co-rich as well as to the Co-deficient side whereas the phases Gd 2 Co 17 and Sm 2 Co 17 show almost no Co solubility. A tentative diagram is presented for the phase relationships involved in the transition between the two allotropic forms of Gd 2 Co 17 . The occurrence of various types of microstructures in as-cast and annealed RCo 5 samples is explained in terms of the peculiar shape of the solvus of the RCo 5 homogeneity regions at high temperatures.

Hydrocarbon conversion catalyst comprising alumina and aluminum phosphate

Abstract: A catalyst support comprised of alumina and aluminum phosphate is prepared by the hydrolysis of an aluminum alkoxide such as aluminum sec-butoxide with an aqueous solution of phosphoric acid. The alumina-aluminum phosphate prepared in accordance with the invention is a stable material which can be readily formed for use as a support for catalysts useful in a number of hydrocarbon conversion processes. For example, the aluminaaluminum phosphate support may be impregnated with various combinations of cobalt, nickel, tungsten and molybdenum for use as a catalyst for the desulfurization and denitrogenation of both light and heavy petroleum fractions. The support material may also be combined with zeolitic materials for use in hydrocracking or catalytic cracking or combined with noble metals for use in the reforming of petroleum feedstocks.

Production of amines from alcohols

Abstract: An improved method of preparing amines by reaction of alcohols with ammonia or primary or secondary amines at elevated temperature and superatmospheric pressure in the presence of hydrogen and a hydrogenation catalyst containing cobalt, nickel and copper, the improvement comprising using a catalyst which contains (calculated on the metal content of the catalyst) from 70 to 95% by weight of a mixture of cobalt and nickel and from 5 to 30% by weight of copper, the ratio by weight of cobalt to nickel being from 4:1 to 1:4. The amines prepared in this way are suitable for the production of emulsifying agents, plant protection agents and vulcanization accelerators.

The crystal and molecular structure of tris (acetylacetonato)-aluminum(iii) and -cobalt(iii)

Abstract: The structures of tris(acetylacetonato)-Al(III) and -Co(III), M(CH3COCHCOCH3)3, have been determined by 3-dimensional single crystal X-ray diffraction methods These isomorphous complexes belong to the monoclinic crystal system and contain four molecules in the space group P21/c The unit cell dimensions of tris(acetylacetonato)Al(III) are: a = 14069 ± 0009 A, b = 7568 ± 0005 A, c = 16377 ± 0010 A, β = 99°00′ ± 5′ The unit cell dimensions of tris(acetylacetonato)Co(III) are: a = 13951 ± 0009 A, b = 7470 ± 0005 A, c = 16222 ± 0011 A, β = 98°29′ ± 5′ 1505 photographically recorded reflections for the Co complex and 1569 reflections for the Al complex were evaluated by microphotometer techniques Refinement was by least squares methods to a conventional unweighted R factor of 007 for the Al complex and 008 for the Co complex The structures consist of discrete molecules held together by van der Waals forces Distortions of the octahedral configuration of O atoms about the Co atom are

The aggregation and reaction with oxygen of the tetrasodium salt of cobalt phthalocyanine-4,4',4'',4'''-tetrasulphonic acid

Abstract: The reversible addition of molecular oxygen to the tetrasodium salt of cobalt phthalocyanine-4,4?,4?,4??-tetrasulphonic acid in aqueous solution has been confirmed. Visible absorption spectra of the monomeric and dimeric species and of the oxygen adduct have been determined. A monomer-dimer system prevails at neutral pH, low ionic strength, and low dye concentrations. The oxygen adduct and the dimeric form of the dye predominate in alkaline solution.

Metal oxide catalytic compositions

Abstract: Compounds having the perovskite-type AB03 structure wherein 1 to 20% of the B site cations are Ru or Pt, the remainder consisting essentially of cobalt, preferably partially tetravalent and the A sites being occupied by a mixture of lanthanide ions and ions of Group IA, IIA, and IVA of the Periodic Table having an ionic radius of about 0.9 to about 1.65 A are useful catalysts for reduction and oxidation reactions, particularly for the cleanup of exhaust gases of internal combustion engines.

µ3-Oxotrimetal acetato-complexes of chromium, manganese, iron, cobalt, rhodium, and iridium

Abstract: New pyridine- and β-picoline-containing oxo-centred complex ions [M3IIIO(CO2Me)6L3]+, M = Cr, Mn, Fe, Co, Rh, and Ir, L = py and β-pic, were synthesised and their redox behaviour studied electrochemically. There is evidence for reduced species in which the oxo-centred triangular structure is maintained in the case of the Mn, Fe, and Co complexes but these could not be isolated. For iridium, complexes [Ir3III,III,IVO(CO2Me)6L3]+2 in which the metal atom is in the mean oxidation state 3⅓ have also been characterised and shown to undergo reduction to the IrIII species. Attempts to prepare oxo-centred complexes of Cu, Ag, Ni, Pd, Pt, and Mo were unsuccessful. The cobalt complex ion [Co3O(CO2Me)6L3]+ appears to be different from the other oxo-centred ions and a structure with both bridging and chelate acetato-groups is proposed.

Structure and properties of reduced LaCoO3

Abstract: Changes occurring in the chemical state, and the crystallographic and electronic structure of LaCoO3 in a reducing atmosphere were determined. These determinations involved the use of thermogravimetric and calorimetric techniques, x‐ray diffraction, and magnetic property measurements. It was shown that the reduction process proceeded through the formation of a series of oxygen‐deficient structures. In the 0–3.25 wt% weight‐loss region, corresponding to the general formula LaCo1−xO3−y, where 0.0