[65027-50-1] · Li2Se2 · Lithium Diselenide · (MW 171.80)
(an excellent nucleophilic agent for synthesis of organic diselenides; can be used for synthesis of bis(trimethylsilyl) selenide1)
Alternate Name: dilithium diselenide.
Solubility: sol H2O; mod sol THF, HMPA, DMF, ethanol.
Form Supplied in: brownish-red solid, or suspension in THF.
Handling, Storage, and Precautions: Li2Se2 is unstable in air and decomposes with separation of Se. It can be stored for a limited period of time under an inert gas atmosphere in a refrigerator. It should be used directly as prepared, without isolation. Use in a fume hood.
Lithium diselenide reacts with many carbon electrophiles. It is a more reactive nucleophile than K2Se2 and Sodium Diselenide.1 Substitution of halogens, mesyl, tosyl, or diazonium groups takes place to form bisaryl or bisalkyl diselenides in fair yields (eq 1).1,4 In some cases, aromatic and heteroaromatic diselenides are accompanied by minor amounts of selenides as byproducts.1
The electrophilic carbon atoms of the oxirane or the lactone ring are attacked by the diselenide anion formed from Li2Se2 and ring opening leads to bis(b-hydroxyalkyl) diselenides (eq 2) or bis(carboxyalkyl) diselenides (eq 3).1
Bis(trimethylsilyl) Selenide is obtained when Chlorotrimethylsilane is treated with Li2Se2 (eq 4).1
Jacek Mlochowski & Ludwik Syper
Technical University of Wroclaw, Poland