Synthesis and Characterization of Novel Aluminum-Arsenic Compounds. Crystal Structure of [Et2AlAs(SiMe3)2]2

The viability of dehalosilylation and lithium chloride elimination reactions for use in the preparation of compounds containing core rings of the type Al-As-Al-As and Al-As-Al-Cl was investigated. The second fully characterized aluminum-arsenic dimer, [Et2AlAs(SiMe3)2]2 (1), was isolated from a coupling reaction between Et2AlCl and LiAs(SiMe3)3 carried out at −78 °C. Reactions between Et2AlCl and As(SiMe3)3 in 1:1 and 2:1 mole ratios at ambient temperature failed to give the expected dehalosilylation products, instead yielding the adduct Et2(Cl)Al·As(SiMe3)3 (2). As evidenced by ¹H NMR spectra, an NMR tube sample of 2 in benzene-d6 did undergo internal dehalosilylation to give 1 when heated to 87 °C in an oil bath. X-ray crystallographic analysis of 1 confirms its dimeric solid-state structure and shows the Al-As-Al-As ring to be planar. Compound 1 crystallizes in the monoclinic system, space group C2/c (C2h⁶), with four molecules in a unit cell of dimensions a = 18.214 (2) Å, b = 9.542 (1) Å, c = 20.453 (2) Å, and β = 99.89 (1)°. © 1992, American Chemical Society. All rights reserved.

Duke Scholars

Author Andrew T. McPhail Chemistry