Coordination compounds of cobalt

Since there are a number of complexes that might conceivably be formed from most combinations of reagents (Exercise 8), the obtaining of a desired complex in substantial yield is in many cases an art. In identifying coordination compounds of cobalt, halogen atoms held in the complex ion are distinguished from anionic halides by treatment with Ag+. This precipitates anionic chloride, bromide, and iodide immediately, but eom-plexed halide precipitates only slowly. Thus, with the purpose compound... 

A coordination compound of cobalt(III) contains four ammonia molecules, one sulfate ion, and one chloride ion. Addition of aqueous BaCli solution to an aqueous solution of the compound gives no precipitate. Addition of aqueous AgN03 to an aqueous solution of the compound produces a white precipitate. Propose a structure for this coordination compound. 

In a review, discussing a wide range of previous studies of isomerization in coordination compounds of cobalt or chromium with several representative diamines, Yamaguchi et al. [59] concluded that, even in the solid state, any ligand in these metal coordination compounds was unexpectedly easy to move. Most of these isomerizations, including 22 reactions trans to cis and cis to trans steps), occurred between about 400 and 520 K. 

Five coordinate compounds of cobalt are now comparatively common, though only on nitrosyl (dimethyldithiocarbonato) cobalt(I) has a detailed X ray examination been performed (1). This has been shown to have a square pyramidal structure with the N-0 bond inclined at 139 to the pyramidal axis, forming an unsymmetrical tr bond with the cobalt atom. 

A3 FIVE COORDINATE COMPOUNDS OF COBALT, A. Earnshaw,... 

Base hydrolysis (substitution by hydroxide ion) of coordination compounds of cobalt(III) with ligands containing an N-H group. The unusual rate equation is... 

Vitamin B12 is a coordination compound with cobalt as its central atom. It contains 4.4% cobalt by mass and has a molar mass of 1.3 X 103 g/mol. How many cobalt atoms are in a molecule of vitamin B12 ... 

Potassium Hexanitrocobaltate(III). Add a little acetic acid and an excess of potassium nitrite to a cobalt(II) salt solution. Heat the mixture. What gas evolves What precipitates Write the equation of the reaction. What is the coordination number of cobalt in this compound ... 

Evidence forcoball(l) was first obtained from the electrolytic reduclion of cyano-compounds and some of the reduced species have been isolated. There arc also many cohaltfl) coordination compounds of Ihe organomelallic class carbonyl, isonitriles, and unsaturated hydrocarbon derivatives. The oxidation state cobalt(O) may be represented in the eyano-Lompound which has been formulated as Ks[Cu (CN)b. It has been prepared as an air-sensitive brown-violet compound by reducing a liquid ammonia solution of Kj Co(CN)f,l with an excess of K tnctal. The only other known coball(O) species arc organomelallic compounds. 

Coordination compounds of nickel <79AG(E)683> and cobalt <70BCJ3604> with trithiapen-talenes have been described. 2,5-Diphenyl-1,6,6aA4-trithiapentalene reacts with palladium dichloride, in the presence of triphenylphosphine, giving a coordination compound (15) in which a benzene ring is directly linked to palladium <79AG(E)684). 

In Volume V of this series, syntheses were presented for coordination compounds of 2,2 -iminodipyridine [di-2-pyridylamine, NH(C6H4N)2] with copper(II) and cobalt-(II). Nickel(II) has also been shown to coordinate with this ligand. A similar behavior is exhibited by zinc salts, which form 1 1 derivatives if a 1 1 mol ratio of reactants is used. The specific choice of a solvent medium for synthesis is dictated by the solubility of the zinc compound. Either acetone or methanol may be used with zinc chloride, methanol with zinc acetate, and pyridine with zinc cyanide. 

The Alsatian-Swiss chemist Alfred Werner pioneered the field of coordination chemistry in the late nineteenth century. At that time, a number of compounds of cobalt(III) chloride with ammonia were known. They had the following chemical... 

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