Chemie polyfunktioneller Moleküle. 93. Die halogenierende Ringspaltung des As3-Nortricyclans, 4-Methyl-1,2,6-triarsatricyclo[2.2.1.02,6]heptan Darstellung und Eigenschaften von 2,6-Dihalogen-4-methyl-1,2,6-triarsabicyclo[2.2.1]heptanen
Chemistry of Polyfunctional Molecules. 93. Halogenating Ring Cleavage of As3-Nortricyclane 4-Methyl-1,2,6-triarsatricyclo2.2.1.02,6]heptane. Preparation and Properties of 2,6-Dihalogeno-4-methyl-1,2,6-triarsabicyclo2.2.1]heptanes The reaction of the As3-nortricyclane CH3C(CH2As)3 ( 1 ) with PCl5, Br2, or I2 in a molar ratio of 1:1 leads to the new 2,6-dihalogeno-4-methyl-1,2,6-triarsabicyclo2.2.1]heptanes CH3C(CH2As)3X2 (X = Cl, Br, I; 2a–c ). Application of a molar ratio of 1:2 results in the formation of 1,1,1-tris(dihalogenoarsinomethyl)ethanes CH3C(CH2AsX2)3 ( 4a–c ) in rather poor yields; 1H-NMR spectroscopic studies suggest that 4a–c are formed via 2a–c and the tetrahalogenodiarsacyclopentane derivatives ( 3a–c ); the latter can not be isolated from their solutions. 4a–c are obtained in very good yields by treatment of 1 with the halogenating agents in a molar ratio of 1:3 Comproportionation of 1 with 4a–c (molar ratio of 2:1) gives also 2a–c . Whereas in CD2Cl2 or CS2 disproportionation of 2a leads to an equilibrium between 1 and 4a , which is formed via the intermediate 3a . The homologues 2b, c are stable with respect to disproportionation in both solvents.
