Preparation and chemistry of Me3SiCH2AsH2; Preparation of [Me3SiCH2(H)AsGaPh2]3, a trimeric mono(arsino)gallane containing a hydrogen bonded to arsenic. Isolation and X-ray crystal structure of (Me3SiCH2As)5

Reduction of Me3SiCH2AsCl2 (I) with LiA1H4 at -78°C afforded Me3SiCH2 AsH2 (II) and reaction of II with Ph3Ga produced [Me3SiCH2(H)AsGaPh2]3 (III) which was characterized by partial elemental analysis (C and H), ¹H NMR spectroscopy and a cryoscopic molecular weight determination. Based on ¹H NMR data, [Me3SiCH2 (H)AsGaMe2]3 (IV) was produced by the reaction of II with Me3Ga; however, only H2, Me4Si, (Me3SiCH2As)5 (VI) and unreacted (Me3SiCH2)3Ga were identified after allowing the latter to react with II. Reaction of 2 equiv. of Me3SiCl with a mixture of II and n-BuLi (1 : 2 mole ratio) afforded Me3SiCH2As(SiMe3)2 (V). The monosilylated arsine was not isolated when 1 equiv. of Me3SiCl was allowed to react with combined II and n-BuLi (1 : 1 mole ratio); rather, a mixture of II and V resulted. Attempted preparations of (Me3SiCH2AsGaPh)n, are described. The ring compound, VI, was prepared by reaction of I with a mixture of Me3SiCl and Mg in THF. The molecular structure of this cycloarsane was determined by single-crystal X-ray diffraction methods. Pale yellow crystals of VI belong to the monoclinic system with four molecules occupying the general positions of space group P21/c(C2h⁵)with cell constants: a = 9.952(1), b = 30.245(9), c = 13.000(3) Å, β = 91.69(1)°, V = 3911.3 Å ³, Z = 4. © 1990.

Duke Scholars

Author Andrew T. McPhail Chemistry