CoCl2 Cobalt

CoCl2 COBALT CHLORIDE 90.9544 -1.2963E+04 -2.7733E+01 7.3497E-03 -8.1551E... 

CoCl2 COBALT CHLORIDE 60.291 6.1086E-02 1.8571E-16 -1.9975E-19 7.7177E-23 298 1013 solid... 

CoCl2 Cobalt(II) chloride, 5 154 [Co(en)2Cl2]Cl cis- and tram-Di-chlorobis (ethylenediamine)co-balt(III) chloride, 2 222, 223, 224... 

Cobalt chloride, C0CI2. Obtained as red crystals of CoCl2 6H20 from aqueous solution, CoCU HiO and C0CI2 are blue as is the (CoCU) " ion. No higher chloride is known although cobalt-haloammines, e.g. (Co(NH3)5C1) are stable. 

Although less active, the cobalt system CoCl2/PPh3/NaBH4 affords a 90/10 mixture of 1,2- and 1,4-addition products in 98% yield at room temperature [172]. Palladium catalysts are more efficient (Eq. 4.43) [173]. 

Under relatively mild conditions the Ru/C catalyst poisoned with Sn (lines 1 and 2), the Ir/C catalyst (lines 14 and 15), and the Raney-cobalt catalyst modified with CoCl2 (line 19) seem likely systems to try when initiating a search for an effective method for selectively hydrogenating the C=0 bond in an a, 3-unsaturated aldehyde. 

Low-valent cobalt pyridine complexes, electrogenerated from CoCl2 in DMF containing pyridine and associated with a sacrificial zinc anode, are also able to activate aryl halides to form arylzinc halides.223 This electrocatalytic system has also been applied to the addition of aryl bromides containing an electron-withdrawing group onto activated alkenes224 and to the synthesis of 4-phenylquinoline derivatives from phenyl halides and 4-chloroquinoline.225 Since the use of iron as anode appeared necessary, the role of iron ions in the catalytic system remains to be elucidated. 

Three color changes were observed blue, violet and red. From the information provided, the blue form appeared to be the anhydride, CoCl2. When exposed briefly to air containing water vapor, the anhydrous cobalt chloride turned violet, CoCl2 2H20. Upon further standing in air, the dihydrate was converted to the fully hydrated form, CoCl2 6 H20. The color of the anhydride-hydrate depended upon the relative humidity of the air to which it was exposed. 

Cobalt(lI) halides can be obtained by direct combination of the elements, or by dehydration of their hydrates. Anhydrous cobalt(II) chloride is blue, and the solid contains octahedrally-coordinated cobalt the hydrated salt CoCl2,6H20 is pink, with each cobalt surrounded by four water molecules and two chloride ions in a distorted octahedron. 

The only other known transition metal terphenyl derivative is the blue, crystalline cobalt species Co(ju.-Br)C6H3-2,6-Mes2(THF) 239 (Fig. 12). It is isostructural to the corresponding magnesium derivative discussed earlier. It was synthesized via the reaction of CoCl2 with the Grignard reagent,... 

The catalysis of the selective oxidation of alkanes is a commercially important process that utilizes cobalt carboxylate catalysts at elevated (165°C, 10 atm air) temperatures and pressures (98). Recently, it has been demonstrated that [Co(NCCH3)4][(PF6)2], prepared in situ from CoCl2 and AgPF6 in acetonitrile, was active in the selective oxidation of alkanes (adamantane and cyclohexane) under somewhat milder conditions (75°C, 3 atm air) (99). Further, under these milder conditions, the commercial catalyst system exhibited no measurable activity. Experiments were reported that indicated that the mechanism of the reaction involves a free radical chain mechanism in which the cobalt complex acts both as a chain initiator and as a hydroperoxide decomposition catalyst. 

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