Chromium(II) bromide

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Chromium(II) bromide
Kristallstruktur Cadmiumiodid.png
Names
IUPAC name
Chromium(II) bromide
Other names
Chromium dibromide, Chromium bromide, Chromous bromide
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
UNII
  • InChI=1S/2BrH.Cr/h2*1H;/q;;+2/p-2
    Key: XZQOHYZUWTWZBL-UHFFFAOYSA-L
  • [Cr+2].[Br-].[Br-]
Properties
CrBr2
Molar mass 211.804 g·mol−1
AppearanceWhite solid [1]
Density 4.236 g/cm3 [1]
Melting point 842 °C (1,548 °F; 1,115 K) [1]
soluble, exothermal blue solution [1]
Structure
monoclinic [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Chromium(II) bromide is the inorganic compound with the chemical formula CrBr2. Like many metal dihalides, CrBr2 adopts the "cadmium iodide structure" motif, i.e., it features sheets of octahedral Cr(II) centers interconnected by bridging bromide ligands. It is a white solid that dissolves in water to give blue solutions that are readily oxidized by air.

Synthesis and reactions

It can be prepared by reduction of chromium(III) bromide with hydrogen gas for 6–10 hours at 350-400 °C, cogenerating hydrogen bromide: [2]

2 CrBr3 + H2 → 2 CrBr2 + 2 HBr

Treatment of chromium powder with concentrated hydrobromic acid gives a blue hydrated chromium(II) bromide, which can be converted to a related acetonitrile complex. [3]

Cr + n H2O + 2 HBr → CrBr2(H2O)n + H2

Related Research Articles

Hydrobromic acid is an aqueous solution of hydrogen bromide. It is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C (255.7 °F) and contains 47.6% HBr by mass, which is 8.77 mol/L. Hydrobromic acid is one of the strongest mineral acids known.

<span class="mw-page-title-main">Hydrogen bromide</span> Chemical compound

Hydrogen bromide is the inorganic compound with the formula HBr. It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temperature. Aqueous solutions that are 47.6% HBr by mass form a constant-boiling azeotrope mixture that boils at 124.3 °C (255.7 °F). Boiling less concentrated solutions releases H2O until the constant-boiling mixture composition is reached.

<span class="mw-page-title-main">Chromium(III) chloride</span> Chemical compound

Chromium(III) chloride (also called chromic chloride) is an inorganic chemical compound with the chemical formula CrCl3. It forms several hydrates with the formula CrCl3·nH2O, among which are hydrates where n can be 5 (chromium(III) chloride pentahydrate CrCl3·5H2O) or 6 (chromium(III) chloride hexahydrate CrCl3·6H2O). The anhydrous compound with the formula CrCl3 are violet crystals, while the most common form of the chromium(III) chloride are the dark green crystals of hexahydrate, CrCl3·6H2O. Chromium chlorides find use as catalysts and as precursors to dyes for wool.

<span class="mw-page-title-main">Triphenylphosphine</span> Chemical compound

Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to PPh3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether.

<span class="mw-page-title-main">Chromium(II) chloride</span> Chemical compound

Chromium(II) chloride describes inorganic compounds with the formula CrCl2(H2O)n. The anhydrous solid is white when pure, however commercial samples are often grey or green; it is hygroscopic and readily dissolves in water to give bright blue air-sensitive solutions of the tetrahydrate Cr(H2O)4Cl2. Chromium(II) chloride has no commercial uses but is used on a laboratory-scale for the synthesis of other chromium complexes.

<span class="mw-page-title-main">Zinc bromide</span> Chemical compound

Zinc bromide (ZnBr2) is an inorganic compound with the chemical formula ZnBr2. It is a colourless salt that shares many properties with zinc chloride (ZnCl2), namely a high solubility in water forming acidic solutions, and good solubility in organic solvents. It is hygroscopic and forms a dihydrate ZnBr2·2H2O.

<span class="mw-page-title-main">Chromyl chloride</span> Chemical compound

Chromyl chloride is an inorganic compound with the formula CrO2Cl2. It is a reddish brown compound that is a volatile liquid at room temperature, which is unusual for transition metal compounds.

<span class="mw-page-title-main">Vanadium(III) bromide</span> Chemical compound

Vanadium(III) bromide, also known as vanadium tribromide, describes the inorganic compounds with the formula VBr3 and its hydrates. The anhydrous material is a green-black solid. In terms of its structure, the compound is polymeric with octahedral vanadium(III) surrounded by six bromide ligands.

Zirconium(IV) bromide is the inorganic compound with the formula ZrBr4. This colourless solid is the principal precursor to other Zr–Br compounds.

Tin(II) bromide is a chemical compound of tin and bromine with a chemical formula of SnBr2. Tin is in the +2 oxidation state. The stability of tin compounds in this oxidation state is attributed to the inert pair effect.

Bromine compounds are compounds containing the element bromine (Br). These compounds usually form the -1, +1, +3 and +5 oxidation states. Bromine is intermediate in reactivity between chlorine and iodine, and is one of the most reactive elements. Bond energies to bromine tend to be lower than those to chlorine but higher than those to iodine, and bromine is a weaker oxidising agent than chlorine but a stronger one than iodine. This can be seen from the standard electrode potentials of the X2/X couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V). Bromination often leads to higher oxidation states than iodination but lower or equal oxidation states to chlorination. Bromine tends to react with compounds including M–M, M–H, or M–C bonds to form M–Br bonds.

<span class="mw-page-title-main">Iron(II) bromide</span> Chemical compound

Iron(II) bromide refers to inorganic compounds with the chemical formula FeBr2(H2O)x. The anhydrous compound (x = 0) is a yellow or brownish-colored paramagnetic solid. The tetrahydrate is also known, all being pale colored solids. They are common precursor to other iron compounds.

<span class="mw-page-title-main">Copper(I) bromide</span> Chemical compound

Copper(I) bromide is the chemical compound with the formula CuBr. This diamagnetic solid adopts a polymeric structure akin to that for zinc sulfide. The compound is widely used in the synthesis of organic compounds and as a lasing medium in copper bromide lasers.

<span class="mw-page-title-main">Barium bromide</span> Chemical compound

Barium bromide is the chemical compound with the formula BaBr2. It is ionic and hygroscopic in nature.

<span class="mw-page-title-main">Cobalt(II) bromide</span> Chemical compound

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.

<span class="mw-page-title-main">Silicon tetrabromide</span> Chemical compound

Silicon tetrabromide, also known as tetrabromosilane, is the inorganic compound with the formula SiBr4. This colorless liquid has a suffocating odor due to its tendency to hydrolyze with release of hydrogen bromide. The general properties of silicon tetrabromide closely resemble those of the more commonly used silicon tetrachloride.

<span class="mw-page-title-main">Chromium(II) sulfate</span> Chemical compound

Chromium(II) sulfate is an inorganic compound with the chemical formula CrSO4. It often comes as hydrates CrSO4·nH2O. Several hydrated salts are known. The pentahydrate CrSO4·5H2O is a blue solid that dissolves readily in water. Solutions of chromium(II) are easily oxidized by air to Cr(III) species. Solutions of Cr(II) are used as specialized reducing agents of value in organic synthesis.

<span class="mw-page-title-main">Chromium(III) bromide</span> Chemical compound

Chromium(III) bromide is an inorganic compound with the chemical formula CrBr3. It is a dark colored solid that appears green in transmitted light but red with reflected light. It is used as a precursor to catalysts for the oligomerization of ethylene.

Titanium(III) bromide is the inorganic compound with the formula TiBr3. It is a blue black paramagnetic solid with a reddish reflection. It has few applications, although it is a catalyst for the polymerization of alkenes.

<span class="mw-page-title-main">Chromium(II) iodide</span> Chemical compound

Chromium(II) iodide is the inorganic compound with the formula CrI2. It is a red-brown or black solid. The compound is made by thermal decomposition of chromium(III) iodide. Like many metal diiodides, CrI2 adopts the "cadmium iodide structure" motif, i.e., it features sheets of octahedral Cr(II) centers interconnected by bridging iodide ligands. Reflecting the effects of its d4 configuration, chromium's coordination sphere is highly distorted.

References

  1. 1 2 3 4 5 Perry, Dale L. (2011). Handbook of Inorganic Compounds, Second Edition. Boca Raton, Florida: CRC Press. p. 120. ISBN   978-1-43981462-8 . Retrieved 2014-01-10.
  2. Brauer, Georg (1965) [1962]. Handbuch Der Präparativen Anorganischen Chemie [Handbook of Preparative Inorganic Chemistry] (in German). Vol. 2. Stuttgart; New York, New York: Ferdinand Enke Verlag; Academic Press, Inc. p. 1341. ISBN   978-0-32316129-9 . Retrieved 2014-01-10.
  3. Holah, David G.; Fackler, John P. (1967). "Chromium(II) Salts and Complexes". Inorganic Syntheses. Vol. 10. pp. 26–35. doi:10.1002/9780470132418.ch4. ISBN   9780470131695.