EtMe3Sb

EtMe3Sb is the shorthand designation for tris(ethyl)methylantimony, an organoantimony compound with the empirical formula C5H14Sb. The molecule consists of one ethyl group and three methyl groups bonded to a central antimony atom, giving it a tetrahedral geometry. This reagent is typically isolated as a light, off‑white liquid with a faint odor and a relatively high vapor pressure, enabling efficient handling in catalytic amounts.

The compound is prepared by alkylation of antimony trichloride with an excess of an organolithium or Grignard reagent, then quenched and purified by distillation. The synthesis often yields a mixture of regioisomers; selective formation of EtMe3Sb is achieved by controlling stoichiometry and temperature. In solution, EtMe3Sb is soluble in polar organic solvents such as tetrahydrofuran, dichloromethane and THF, but shows limited solubility in non‑polar media.

EtMe3Sb functions primarily as a Lewis acid or a mild organoantimony nucleophile in organic synthesis. It participates in atom transfer alkylation, facilitates the formation of heterocycles through cycloaddition reactions, and serves as a catalyst for the rearrangement of certain organosilicon compounds. Its steric bulk and relatively low Lewis acidity compared to other organoantimony reagents make it useful for selective transformations that require gentle activation.

Safety data indicate that EtMe3Sb is toxic by ingestion, inhalation, or dermal contact due to the presence of antimony. It is flammable; therefore, it should be stored in a cool, dry place, away from oxidizing agents. Protective equipment, such as gloves and eye protection, is recommended during handling. Disposal should follow local regulations for hazardous organometallic waste.