Cobalt complexes cyanates

Cobalt complexes, 635-882 ADP, 760 amides, 682 arsenates, 774 arsenic ligands, 767-775 ATP, 760 bipyridyl, 691 bis(dithiolates), 876 carboxylates, 790 cyanates, 679 cyanides reduction, 646 disulfides, 829... 

For colorimetric or gravimetric determination l-nitroso-2-naphthol can be used. For chromatographic ion exchange (qv), cobalt is isolated as the nitroso-(R)-salt complex. The cyanate complex is used for photometric determination and the thiocyanate for colorimetry. A rapid chemical analysis of... 

Determination of cobalt as cobalt tetrathiocyanatomercurate(II) (mercurithio-cyanate) Discussion. This method is based upon the fact that cobalt (II) in almost neutral solution forms a blue complex salt Co [ Hg( SCN )4] with a reagent... 

The scope of this chapter is based on the analogous one by Naso and Marchese published in 19831. Since the time of their review, the focus of work in this area has shifted somewhat, and sections have been added or omitted to reflect that focus. New sections covering chromium(II)-mediated reactions of halides and covering cobalt-mediated radical reactions of halides have been added. In view of the relatively mature nature of the areas, sections dealing with 7c-allylnickel complexes, iron oxyallyl cations and cyanation reactions have been omitted. 

Table 19 Cyanate, Thiocyanato and Selenocyanato Complexes of Cobalt(IIl)...

The first mechanism is. in fact, reminiscent of the well-known copper-catalyzed dimerization of acetylene viny(acetylene being the main by-product of this process. This side reaction can, however, be inhibited to some extent by the use of cobalt salts as additives [IS]. The cyanation of acetylene and of alkenyl halides is also promoted by Co and Ni cyanides and Pd catalysis. A reducing reagent, such as Zn or NaBll4, has been used in conjunction with cobalt cyanide complexes, and the formation of. succinonitrile has been reported to result from the basebase-catalyzed hydrocyanation of acrylonitrile. 

A number of mixed-hgand cyanates of cobalt(III) and (II) are given in Table XXVII, which lists only a representative sample of the large number of such complexes available. In many cases the results were discussed in terms of variations in u or tt bonding or of steric effects. These discussions will not be rehearsed in this section but, where relevant to this review, will be referred to later. With the exception of... 

To facilitate the program it was decided to study the cobalt(II)-thio-cyanate complex system which was as accessible to direct assay in the exchanger phase as it was in the solution phase by absorption spectrophotometry in the visible region. Both Co(II) and Co(SCN) exhibit sizably different spectral absorption properties in the visible region. Assuming that the presence of higher complexes than one to one in the cation... 

Cobaltaie(l -), dodecacarbonylirontri-, tetraethylammonium, 27 188 Cobaltate(l -), dodecacarbonylirontri-, (triphenylphosphine)gold(l -(-), 27 188 -------, dodecacarbonylrutheniumtri-, tetraethylammonium, 26 358 Copper, (acetonitrile)dodecacarbonyltrico-balt ruthenium-, 26 359 Crystal growth, 26 377 Cyanate, tungsten complex, 26 42 Cycloheptatriene, molybdenum complex, 27 4... 

Meprobamate is hydrolyzed in an alkaline alcoholic medium to yield a cyanate which forms a blue colored complex with cobalt ions. For analyses >37,38,39 the intensity of the color has been determined at 603 mu. 

These results coupled with the greater success of nickel and palladium catalysts may explain the long interval preceding the next report on cobalt catalysts . Cobalt(I) complexes (see Table 1) are, however, effective hydrocyanation catalysts, not only in hydro-cyanating olefins such as 4-pentenenitrile, but also are effective for isomerizing 2-methyl-... 

Interest continues in the effects of micellar agents on rates of inorganic reactions. Aquation of oxalato-cobalt(m) and -chromium(iii) complexes is mentioned in a review of reversed micellar systems predicted and actual rates have been compared for a variety of reactions, including the mercury(n)-catalysed aquation of [CoX(NH3)g] + cations. Micellar effects on uncatalysed aquation of cis- and of tra j -[CoCl2(en)2]+ are small (as expected) but real. Other reactions for which the kinetic consequences of micelle or polyelectrolyte addition have been d cribed include complex formation from nickel(ii), the conversion of ammonium cyanate into urea, and the hydrolysis of pyrophosphate. ... 

Z)-Alk-2-enenitriles are also available from the hydrocyanation of acetylenes, which occurs with cis stereospecificity when catalysed by a nickel(O) complex, and from the stereoselective cyanation of vinyl halides, catalysed by tetracyano-cobaltate(i). The latter procedure is equally applicable to the stereoselective synthesis of the corresponding ( )-isomers. Also, the ( )- and (Z)-isomers (17) and (18) react with piperidine with retention of configuration to provide (19) and (20) respectively (Scheme 30). In contrast, the corresponding reaction with sodium methoxide gives rise to the (Z)-isomer only. 

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