Cobalt(II) bromide

Cobalt(II) bromide
	; Anhydrous cobalt(II) bromide in a vial
Identifiers
CAS Number	7789-43-7 ;
3D model (JSmol)	Interactive image;
ChemSpider	23012 ;
ECHA InfoCard	100.029.242
EC Number	232-166-7;
PubChem CID	24610;
RTECS number	GF9595000;
UNII	7M7RX75BAL ;
UN number	3077
CompTox Dashboard (EPA)	DTXSID50894158 ;
	InChI InChI=1S/2BrH.Co/h21H;/q;;+2/p-2 Key: BZRRQSJJPUGBAA-UHFFFAOYSA-L ; InChI=1/2BrH.Co/h21H;/q;;+2/p-2 Key: BZRRQSJJPUGBAA-NUQVWONBAJ;
	SMILES [Co](Br)Br;
Properties
Chemical formula	CoBr2, CoBr2.6H2O, CoBr2.2H2O
Molar mass	218.7412 g/mol (anhydrous) ; 326.74 g/mol (hexahydrate)
Appearance	Bright green crystals (anhydrous) ; Red-purple crystals (hexahydrate)
Density	4.909 g/cm3 (anhydrous) ; 2.46 g/cm3 (hexahydrate)
Melting point	678 °C (1,252 °F; 951 K) (anhydrous) ; 47 °C (hexahydrate)
Solubility in water	anhydrous: ; 66.7 g/100 mL (59 °C) ; 68.1 g/100 mL (97 °C) hexahydrate: ; 113.2 g/100 mL (20 °C)
Solubility	77.1 g/100 mL (ethanol, 20 °C) ; 58.6 g/100 mL (methanol, 30 °C) ; soluble in methyl acetate, ether, alcohol, acetone
Magnetic susceptibility (χ)	+13000·10−6 cm3/mol
Structure
Crystal structure	Rhombohedral, hP3, SpaceGroup = P-3m1, No. 164
Coordination geometry	octahedral
Hazards
Safety data sheet	Fisher Scientific
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H312, H315, H317, H319, H332, H334, H335, H350
Precautionary statements	P201, P202, P261, P264, P270, P271, P272, P280, P281, P285, P301+P312, P302+P352, P304+P312, P304+P340, P304+P341, P305+P351+P338, P308+P313, P312, P321, P322, P330, P332+P313, P333+P313, P337+P313, P342+P311, P362, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	2 0 1
Flash point	Non-flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	406 mg/kg (oral, rat)
Related compounds
Other anions	cobalt(II) fluoride; cobalt(II) chloride; cobalt(II) iodide
Other cations	iron(II) bromide; nickel(II) bromide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Cobalt(II) bromide (CoBr₂) is an inorganic compound. In its anhydrous form, it is a green solid that is soluble in water, used primarily as a catalyst in some processes.

Properties[]

When anhydrous, cobalt(II) bromide appears as green crystals. It is hygroscopic and forms the hexahydrate in air,^[1] which appears as red-purple crystals. The hexahydrate loses four water of crystallization molecules at 100 °C forming the dihydrate:

CoBr₂·6H₂O → CoBr₂·2H₂O + 4 H₂O

Further heating to 130 °C produces the anhydrous form:

CoBr₂·2H₂O → CoBr₂ + 2 H₂O

The anhydrous form melts at 678 °C.^[2]^[3] At higher temperatures, cobalt(II) bromide reacts with oxygen, forming cobalt(II,III) oxide and bromine vapor.

Preparation[]

Cobalt(II) bromide can be prepared as a hydrate by the reaction of cobalt hydroxide with hydrobromic acid:

Co(OH)₂(s) + 2HBr(aq) → CoBr₂·6H₂O(aq)

Anhydrous cobalt(II) bromide may be prepared through the direct reaction of elemental cobalt and liquid bromine.^[4]^[5]^[6]

Reactions and uses[]

The classical coordination compound bromopentaamminecobalt(III) bromide is prepared by oxidation of a solution of cobalt(II) bromide in aqueous ammonia.^[7]

2 CoBr₂ + 8 NH₃ + 2 NH₄Br + H₂O₂ → 2 [Co(NH₃)₅Br]Br₂ + 2 H₂O

Triphenylphosphine complexes of cobalt(II) bromide have been used as a catalysts in organic synthesis.

Safety[]

Exposure to large amounts of cobalt(II) can cause cobalt poisoning.^[8] Bromide is also mildly toxic.

References[]

^ Perry, Dale L. (2011). Handbook of Inorganic Compounds (2nd ed.). Boca Raton: Taylor & Francis. p. 130. ISBN 978-1-4398-1461-1. OCLC 587104373.
^ Cobalt Bromide Supplier & Tech Info American Elements
^ WebElements Periodic Table of the Elements
^ WebElements Periodic Table of the Elements | Cobalt | Essential information
^ Chemical Properties and Reaction Tendencies Archived 2008-02-19 at the Wayback Machine
^ Pilgaard Solutions: Cobalt Archived 2009-01-22 at the Wayback Machine
^ Diehl, Harvey; Clark, Helen; Willard, H. H.; Bailar, John C. (1939). "Bromopentamminocobalti Bromide". Inorganic Syntheses. Inorganic Syntheses. 1. p. 186. doi:10.1002/9780470132326.ch66. ISBN 978-0-470-13232-6.
^ "Archived copy" (PDF). Archived from the original (PDF) on 2007-06-25. Retrieved 2008-04-10.CS1 maint: archived copy as title (link)

This inorganic compound–related article is a stub. You can help Wikipedia by .

[1] Perry, Dale L. (2011). Handbook of Inorganic Compounds (2nd ed.). Boca Raton: Taylor & Francis. p. 130. ISBN 978-1-4398-1461-1. OCLC 587104373.

[2] Cobalt Bromide Supplier & Tech Info American Elements

[3] WebElements Periodic Table of the Elements

[4] WebElements Periodic Table of the Elements | Cobalt | Essential information

[5] Chemical Properties and Reaction Tendencies Archived 2008-02-19 at the Wayback Machine

[6] Pilgaard Solutions: Cobalt Archived 2009-01-22 at the Wayback Machine

[7] Diehl, Harvey; Clark, Helen; Willard, H. H.; Bailar, John C. (1939). "Bromopentamminocobalti Bromide". Inorganic Syntheses. Inorganic Syntheses. 1. p. 186. doi:10.1002/9780470132326.ch66. ISBN 978-0-470-13232-6.

[8] "Archived copy" (PDF). Archived from the original (PDF) on 2007-06-25. Retrieved 2008-04-10.CS1 maint: archived copy as title (link)

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[8]

v t Cobalt compounds
Cobalt(I)	HCo(CO)₄
Cobalt(II)	CoBr₂ Co(CN)₂ CoCO₃ CoC₂O₄ CoCl₂ Co(ClO₃)₂ CoF₂ CoI₂ Co(NO₃)₂ Co₃(PO₄)₂ Co(OAc)₂ CoO Co(OH)₂ CoS CoSO₄ CoSe Co₃P₂ CoH₂
Cobalt(0, III)	CoSi CoGe
Cobalt(II, III)	Co₃O₄
Cobalt(III)	CoCl₃ Co(NO₃)₃ Co₂O₃ CoF₃ Co(OH)₃

Identifiers
Anhydrous cobalt(II) bromide in a vial
CAS Number	7789-43-7^Y
3D model (JSmol)	Interactive image
ChemSpider	23012^Y
ECHA InfoCard	100.029.242
EC Number	232-166-7
PubChem CID	24610
RTECS number	GF9595000
UNII	7M7RX75BAL^Y
UN number	3077
CompTox Dashboard (EPA)	DTXSID50894158
InChI InChI=1S/2BrH.Co/h21H;/q;;+2/p-2^Y Key: BZRRQSJJPUGBAA-UHFFFAOYSA-L^Y InChI=1/2BrH.Co/h21H;/q;;+2/p-2 Key: BZRRQSJJPUGBAA-NUQVWONBAJ
SMILES [Co](Br)Br
Properties
Chemical formula	CoBr₂, CoBr₂.6H₂O, CoBr₂.2H₂O
Molar mass	218.7412 g/mol (anhydrous) 326.74 g/mol (hexahydrate)
Appearance	Bright green crystals (anhydrous) Red-purple crystals (hexahydrate)
Density	4.909 g/cm³ (anhydrous) 2.46 g/cm³ (hexahydrate)
Melting point	678 °C (1,252 °F; 951 K) (anhydrous) 47 °C (hexahydrate)
Solubility in water	anhydrous: 66.7 g/100 mL (59 °C) 68.1 g/100 mL (97 °C) hexahydrate: 113.2 g/100 mL (20 °C)
Solubility	77.1 g/100 mL (ethanol, 20 °C) 58.6 g/100 mL (methanol, 30 °C) soluble in methyl acetate, ether, alcohol, acetone
Magnetic susceptibility (χ)	+13000·10⁻⁶ cm³/mol
Structure
Crystal structure	Rhombohedral, hP3, SpaceGroup = P-3m1, No. 164
Coordination geometry	octahedral
Hazards
Safety data sheet	Fisher Scientific
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H312, H315, H317, H319, H332, H334, H335, H350
Precautionary statements	P201, P202, P261, P264, P270, P271, P272, P280, P281, P285, P301+P312, P302+P352, P304+P312, P304+P340, P304+P341, P305+P351+P338, P308+P313, P312, P321, P322, P330, P332+P313, P333+P313, P337+P313, P342+P311, P362, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	2 0 1
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD₅₀ (median dose)	406 mg/kg (oral, rat)
Related compounds
Other anions	cobalt(II) fluoride cobalt(II) chloride cobalt(II) iodide
Other cations	iron(II) bromide nickel(II) bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y (what is ^YN ?)
Infobox references