LAUSR

Herein, we report an improved synthesis of pentafluoroethylated arsanes. Deprotonation of pentafluoroethane by n-butyllithium yields the readily available pentafluoroethyllithium, which can be handled at low temperatures. Subsequent reaction with arsenic trichloride affords tris(pentafluoroethyl)arsane in good yields. Control of the degree of substitution at the arsenic center is achieved via the introduction of diethylamino protecting groups. The aminoarsanes AsCl2(NEt2) and AsCl(NEt2)2 react smoothly with LiC2F5, enabling the isolation of As(C2F5)2(NEt2) and As(C2F5)(NEt2)2. Cleavage of the diethylamino protecting group with gaseous HCl or HBr affords the corresponding halogenoarsanes. All products represent colorless, volatile liquids, which are characterized by multinuclear NMR spectroscopy. Crystallization of As(C2F5)3 as well as As(C2F5)nCl3-n and As(C2F5)nBr3-n (n = 1,2) is facilitated by in situ crystallization techniques, and the solid-state structures are subsequently determined by X-ray diffraction analysis.