Chromium(II) acetate
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| Names | |
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IUPAC name
Chromium(II) acetate hydrate
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| Other names
chromous acetate,
chromium diacetate, chromium(II) ethanoate |
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| Identifiers | |
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3D model (Jmol)
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| ChemSpider | |
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PubChem CID
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| RTECS number | AG3000000 |
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| Properties | |
| C8H16Cr2O10 | |
| Molar mass | 376.20 g·mol−1 |
| Appearance | brick-red solid |
| Density | 1.79 g/cm3 |
| Melting point | dehydrates |
| soluble in hot water, MeOH | |
| -5104.0·10−6 cm3/mol | |
| Structure | |
| monoclinic | |
| octahedral counting the Cr–Cr bond |
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| quadruple Cr–Cr bond | |
| 0 D | |
| Hazards | |
| Main hazards | could react exothermically in air |
| Related compounds | |
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Related compounds
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Rh2(OAc)4(H2O)2 Cu2(OAc)4(H2O)2, molybdenum(II) acetate |
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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 | |
Chromium(II) acetate hydrate, also known as chromous acetate, is the coordination compound with the formula Cr2(CH3CO2)4(H2O)2. This formula is commonly abbreviated Cr2(OAc)4(H2O)2. This red-coloured compound features a quadruple bond. The preparation of chromous acetate once was a standard test of the synthetic skills of students due to its sensitivity to air and the dramatic colour changes that accompany its oxidation. It exists as the dihydrate and the anhydrous forms.
Cr2(OAc)4(H2O)2 is a reddish diamagnetic powder, although diamond-shaped tabular crystals can be grown. Consistent with the fact that it is nonionic, Cr2(OAc)4(H2O)2 exhibits poor solubility in water and methanol.
The Cr2(OAc)4(H2O)2 molecule contains two atoms of chromium, two ligated molecules of water, and four monoanionic acetate bridging ligands. The coordination environment around each chromium atom consists of four oxygen atoms (one from each acetate ligand) in a square, one water molecule (in an axial position), and the other chromium atom (opposite the water molecule), giving each chromium centre an octahedral geometry. The chromium atoms are joined together by a quadruple bond, and the molecule has D4h symmetry (ignoring the position of the hydrogen atoms). The same basic structure is adopted by Rh2(OAc)4(H2O)2 and Cu2(OAc)4(H2O)2, although these species do not have such short M–M contacts.
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