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| Names | |
|---|---|
| IUPAC name Diselenium dichloride | |
Other names
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| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.030.022 |
| EC Number |
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| UNII | |
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| Properties | |
| Se2Cl2 | |
| Molar mass | 228.84 g·mol−1 |
| Appearance | Reddish-brown oily liquid |
| Density | 2.7741 g/cm3 |
| Melting point | −85 °C (−121 °F; 188 K) |
| Boiling point | 127 °C (261 °F; 400 K) at 0.997 atm |
| insoluble, hydrolyses | |
| Solubility in other solvents | Soluble in chloroform, carbon disulfide, and acetonitrile |
| −94.8·10−6 cm3/mol | |
| Hazards | |
| GHS labelling: | |
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| Danger | |
| H301,H311,H314,H331,H373,H410 | |
| P260,P264,P270,P271,P273,P280,P301+P310,P301+P330+P331,P302+P352,P303+P361+P353,P304+P340,P305+P351+P338,P310,P311,P312,P314,P321,P322,P330,P361,P363,P391,P403+P233,P405,P501 | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Selenium monochloride ordiselenium dichloride is aninorganic compound with the formulaSe2Cl2. Although a common name for the compound is selenium monochloride, reflecting itsempirical formula,IUPAC does not recommend that name, instead preferring the more descriptive diselenium dichloride.
Diselenium dichloride is a reddish-brown, oily liquid that hydrolyses slowly. It exists inchemical equilibrium withSeCl2,SeCl4,chlorine, and elementalselenium.[1] Diselenium dichloride is mainly used as areagent for the synthesis of Se-containing compounds.
Dielenium dichloride has the connectivityCl−Se−Se−Cl. With a nonplanar structure, it has C2molecular symmetry, similar tohydrogen peroxide anddisulfur dichloride, which is referred to asgauche. The Se-Sebond length is 223pm, and the Se-Cl bond lengths are 220 pm. The angle Se – Se – Cl is 104° and thedihedral angle between theCla−Se−Se andSe−Se−Clb planes is 87°.[2]
Early routes to diselenium dichloride involvedchlorination of elementalselenium.[3] An improved method involves the reaction of a mixture of selenium,selenium dioxide, andhydrochloric acid:[4]
A dense layer of diselenium dichloride settles from the reaction mixture, which can be purified by dissolving it in fumingsulfuric acid and reprecipitating it with hydrochloric acid. A second method for the synthesis involves the reaction of selenium witholeum and hydrochloric acid:[4]
The crude diselenium dichloride is removed via separatory funnel. Diselenium dichloride cannot be distilled without decomposition, even at reduced pressure.[4]
Inacetonitrile solutions, it exists in equilibrium withSeCl2 andSeCl4.[5]Selenium dichloride degrades to diselenium dichloride after a few minutes at room temperature:[6]
Diselenium dichloride is an electrophilic selenizing agent, and thus it reacts with simplealkenes to give bis(β-chloroalkyl)selenide and bis(chloroalkyl)selenium dichloride. It convertshydrazones of hindered ketones into the correspondingselenoketones, the structural analogs of ketones whereby the oxygen atom is replaced with a selenium atom.[7] Finally, the compound has been used to introduce bridging selenium ligands between the metal atoms of some iron and chromium carbonyl complexes.[7]
