Cobalt self diffusivity

Chen WK, Jackson RA (1969) Oxygen self-diffusion in undoped and doped cobaltous oxide. J Phys Chem Solids 30 1309-1314... 

A second, and more chemical, verification is due to Finke et al.,21 who also invented the descriptive phrase persistent radical effect and gave a prototype example to the extreme. The thermal reversible 1,3-benzyl migration in a coenzyme B12 model complex leads to the equilibrium of Scheme 9. Earlier work had shown that the reaction involves freely diffusing benzyl and persistent cobalt macrocycle radicals, but the expected self-termination product bibenzyl of benzyl was missing. Extending the detection limits, the authors found traces of bibenzyl and deduced a selectivity for the formation of the cross-products to the self-termination products of 100 000 1 or 99.999%. Kinetic modeling further showed that over a time of 1000 years only 0.18% of bibenzyl would be formed, and this stresses the long-time duration of the phenomenon. 

Characterization of catalysts The zeolite structure was checked by X-ray diffraction patterns recorded on a CGR Theta 60 instrument using Cu Ka, filtered radiation. The chemical composition of the catalysts was determined by atomic absorption analysis after dissolution of the sample (SCA-CNRS, Solaize, France). Micropore volumes were measured by N2 adsorption at 77 K using a Micromeritics ASAP 2000 apparatus and by adsorption of cyclohexane (at P/Po=0.15) using a microbalance apparatus SET ARAM SF 85. Incorporation of tetrahedral cobalt (II) in the framework of Co-Al-BEA and Co-B-BEA was confirmed by electronic spectroscopy [18] using a Perkin Elmer Lambda 14 UV-visible diffuse reflectance spectrophotometer. Acidity measurements were performed by Fourier transform infrared spectroscopy (FT-IR, Nicolet FTIR 320) after pyridine adsorption. Self-supported wafer of pure zeolite (20 mg/cm ) was outgassed at 673 K for 6 hours at a pressure of lO Pa. After cooling at 423 K, the zeolite was saturated with pyridine vapour (30 kPa) for 5 min, evacuated at this temperature for 30 min and the IR spectrum was recorded. 

The formation of (II) provides a quite selective spot test for palladium. Gold must be removed prior to the test because it will cause the development of a deep ruby red in the spot plate test and a diffused violet spot on the paper, apparently due to the reduction of the gold ions to the colloidal metal. Interference may also arise from 0s04 , Os+, Ru+, and RuCle ions because they have distinct self-colors. Mercurous ion causes partial interference by the reduction of part of the palladium to the elementary state, but a positive response can still be seen. It is possible to detect I part of palladium in the presence of 200 parts of platinum or 100 parts of rhodium. Less favorable ratios should be avoided because of the color of these salts. No interference is caused by mercuric and iridic chloride, but free ammonia, ammonium ions, stannous, cyanide, thiocyanate, fluoride, oxalate, and tetraborate ions do interfere. Lead, silver, ferrous, ferric, stannic, cobaltous, nickel, cupric, nitrite, sulfate, chloride, and bromide ions do not interfere. 

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