Seleninyl chloride is the inorganic compound with the formula SeOCl2. It is a colorless liquid. With a high dielectric constant (55) and high specific conductance, it is an attractive solvent. Structurally, it is a close chemical relative of thionyl chloride SOCl2, being a pyramidal molecule.

Preparation and reactions

Seleninyl chloride can be prepared by several methods, and a common one involves the conversion of selenium dioxide to dichloroselenious acid followed by dehydration:

1. SeO2 + 2 HCl → Se(OH)2Cl2

2. Se(OH)2Cl2 → SeOCl2 + H2O

The original synthesis involved the redistribution reaction of selenium dioxide and selenium tetrachloride.

Pure seleninyl chloride autoionizes to a dimer:

1. SeOCl2↔ (SeO)2Cl+ Cl

The SeOCl2 is generally a labile Lewis acid and solutions of sulfur trioxide in SeOCl2 likely form [SeOCl]+[SO3Cl] the same way.

The compound hydrolyzes readily to form hydrogen chloride and selenium dioxide, and very few organic compounds dissolve in it without reaction. At elevated temperatures, it is a strong oxidizer, yielding a chloride, selenium dioxide, and diselenium dichloride.

See also

• Seleninyl bromide (SeOBr2)

• Selenous acid (H2SeO3)

References