Cobalt complexes sulfides

In the treatment of complex sulfide concentrates containing copper, nickel, cobalt, lead, and iron, roasting with a moderate excess of sodium chloride at temperatures up to 400°C prior to leaching with hydrochloric acid has been succeasfully used by Kershner and Hoertel (K4) in the recovery of more than 95% of cobalt, nickel, and copper. The chloridized product is treated with steam at 300°C to make most of the iron insoluble before leaching at a pH of 1.0. The advantages of a salt roast prior to... 

Treatment of an aqueous solution of the cobalt(III) bis(ethylenediamine) complex of 1-aminocyclopropanecarboxylate 1 with ammonium sulfide followed by hydrochloric acid gave cobalt(II) sulfide and the hydrochloride salt of 1-aminocyclopropanecarboxylic acid (2). ... 

The history of coordination chemistry in Japan is briefly presented. Yuji Shibata, founder of coordination chemistry in Japan studied extensively the absorption spectra of complexes of various metals from 1915 to 1917 after returning from Europe. His researches also included the spectro-chemical detection of complex formation in solution, coagulation of arsenic sulfide sols by complex cations, and catalytic oxidation and reduction by metal complexes in solution. Ryutaro Tsuchida published the "spectrochemical series" in 1938 based on the results of his measurements of absorption spectra of cobalt complexes. One of the most remarkable results after World War II is the determination of absolute configurations of cobalt complexes using X-rays in 1954 by Y. Saito and his coworkers. 

Liganded cobalt complexes react with carbon disulfide by addition across one of the C=S bonds to give relatively stable complexes 10. The same complex reacts with carbonyl sulfide to give a liganded carbonyl complex 11 andMesPS. In the reaction of carbon sulfose-lenide at -20 °C the adduct 12 as well as the thiocarbonyl complex 13 are formed, indicating that carbon sulfoselenide can be used for the synthesis of thiocarbonyl compounds. 

Abstract Macromonomers of structure 4. prepared by the free radical polymerization of MMA using cobalt complexes as chain transfer agents, become incorporated into polymer chains by copolymerization but also act as efficient chain transfer agents by an addition-fragmentation reaction. Macromonomers of general structure 1 have been prepared by utilizing appropriately substituted allylic sulfides as chain transfer agents in free radical polymerizations. 

The preliminary results described in this paper suggest that macromonomers derived from chain transfer with cobalt complexes or allylic sulfides have potential for the convenient synthesis of unusual graft copolymers. Work in this area is continuing. 

Mukaiyama s conditions have also been used in other aerobic oxidation reactions of substrates including thiols (Table 5.2, entries 1—4, 10 and 11), alkanes (entries 8, 12 and 14) and alcohols (entries 9 and 13), as well as reactions involving lactone formation via a Baeyer-ViUiger oxidation (entries 5-7) and oxidative decarboxylation (entry 16) [15-17]. While nickel, iron and cobalt aU selectively oxidize thiols to sulfoxides, Co(II) is the most active (entries 1—4) [15 b]. Of particular synthetic interest, the chemoselective and diastereoselective aerobic oxidation of the complex sulfide, exomethylenecepham (entries 10 and 11), was observed with no overoxidation to the suUbne or oxidation of the olefin [16 a]. The diverse substrate scope in entries 1-9 suggest iron and nickel species tend to have similar reactivity with substrates, but cobalt behaves differently. For example, both iron and nickel displayed similar reactivity in Baeyer-Villiger oxidations, with cobalt being much less active (entries 5-7), yet the opposite trend was observed for sulfide oxidation (entries 1—4) [15]. Lastly, illustrating the broad potential scope of Mukaiyama-type oxidations, alcohol oxidation (entries 9 and 13) and oxidative decarbonylation (entry 15) reactions, which are oxidase systems, have also been reported [16b, 17b]. 

Thermogravimetry data shows that all the compounds decompose in two steps. The final product in all cases is the respective metal oxide. However, the intermediate is different in each case for instance, for the iron complex the intermediate is a mixture of Fe(II) and Fe(III) sulfate and the cobalt complex gives cobalt sulfate, whereas the nickel complex gives a mixture of nickel sulfate and nickel sulfide. The formation of these intermediates has been confirmed by observed weight losses in TG as well as chemical analysis of the TG residues after the first step. For the iron complex, the residue obtained at 310 °C is gray and hygroscopic. It gives positive tests for both Fe(II) and Fe(III) in addition to sulfate. 

Bonding Agents. These materials are generally only used in wire cable coat compounds. They are basically organic complexes of cobalt and cobalt—boron. In wire coat compounds they are used at very low levels of active cobalt to aid in the copper sulfide complex formation that is the primary adherance stmcture. The copper sulfide stmcture builds up at the brass mbber interface through copper in the brass and sulfur from the compound. The dendrites of copper sulfide formed entrap the polymer chains before the compound is vulcanized thus hoi ding the mbber firmly to the wire. 

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