Cobalt(II) bromide
chemical compound
Cobalt(II) bromide refers to inorganic compounds with the formula CoBr2·(H2O)n. The anhydrous form (n = 0) is a green solid and the hexahydrate (n = 6) is a red solid. These compounds find some use as catalysts.
Structure
The anhydrous compound has a cadmium iodide structure. The tetrahydrate is molecular, with the formula trans-[CoBr2(H2O)4].
Preparation and reactions
Cobalt(II) bromide form by treating an aqueous suspension of cobalt(II) carbonate with hydrobromic acid according to the following idealized equation:
CoCO3 + 2 HBr + 5 H2O → CoBr2(H2O)6 + CO2
Anhydrous cobalt(II) bromide is hygroscopic. Air exposure eventually forms the hexahydrate in air, 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
The anhydrous compound forms by heating any of the hydrates to >150 °C in a vacuum:
CoBr2(H2O)6 → CoBr2 + 6 H2O
The resulting solid can be purified by vacuum sublimation at > 500 °C.
Further heating to 130 °C produces the anhydrous form:
CoBr2·2H2O → CoBr2 + 2 H2O
At higher temperatures, cobalt(II) bromide reacts with oxygen, forming cobalt(II,III) oxide and bromine vapor.
The coordination compound bromopentaamminecobalt(III) bromide is prepared by oxidation of an aqueous solution of cobalt(II) bromide and ammonia.
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.
This brief starts where responsible research should: with the source description of “Cobalt(II) bromide” as chemical compound. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the science & nature register because the source frames it as chemical compound. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated Aug 6, 2026. The linked authority identifier is Q420300. None of the 0 selected statements returned an explicit reference.
Scientific names, classifications and consensus can change while older terminology persists in catalogues and historical literature. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Check terminology, classification and the date of the cited evidence. Scientific names and technical consensus can change while older records retain historical value.
- Current terminology
- Classification context
- Finding cited technical literature
Primary datasets, specimen catalogues, standards bodies and the most recent peer-reviewed literature.
Three-step research path
- Establish the record: confirm the title “Cobalt(II) bromide”, its source revision and the description used here.
- Expand the search: follow Cobalt(II) bromide primary sources, Cobalt(II) bromide archive and Cobalt research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Cobalt(II) bromide”?
- Is the terminology current, historical or disputed?
- Which observation, specimen, dataset or publication supports the account?
Search terms from this dossier
This entry incorporates text from “Cobalt(II) bromide” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.