Reactions of H3Al NMe3 with E(SiMe3)3 (E = P, As). Structural Characterization ofthe Trimer H2AlP(SiMe3)23 and Base-Stabilized Adduct H2AlAs(SiMe3)2 NMe3, and Their Thermal Decomposition Toward Nanocrystalline AlP and AlAs, Respectively

摘要

Dehydrosilylation reactions in diethyl ether between H3Al.NMe3 and E(SiMe3)3afforded for E = P a high yield of the trimer H2AlP(SiMe3)23 (1) while for E = As a monomeric base-stabilized adduct H2AlAs(SiMe3)2.NMe3 (2) as well as its degradation solid product were obtained. No reaction occurred for E = N. The single-crystal X-ray structure determination for 1 yielded a planar six-membered ring of alternating four-coordinated Al and P centers. The structural solution for 2 revealed the monomeric unit H2AlAs(SiMe3)2 stabilized by coordination of NMe3 at the Al-site. Pyrolysis of 1 at 450 deg C promoted further dehydrosilylation and yielded a product which by XRD spectroscopy showed the onset of AlP crystallinity while at 950 deg C afforded nanocrystalline AlP with 5 nm average particle size. Pyrolysis of 2 at 450 deg C resulted in the formation of nanocrystalline AlAs with 2 nm average particle size. Under applied pyrolysis conditions for 1 and 2, the target elimination-condensation pathwayvia dehydrosilylation was accompanied by other decomposition side reactions and retention of some contaminant residues.