Reactions of H(3)Al.NMe(3) with E(SiMe(3))(3) (E = P, As). Structural Characterization of the Trimer [H(2)AlP(SiMe(3))(2)](3) and Base-Stabilized Adduct [H(2)AlAs(SiMe(3))(2)].NMe(3) and Their Thermal Decomposition toward Nanocrystalline AlP and AlAs, Respectively.
Dehydrosilylation reactions in diethyl ether between H(3)Al.NMe(3) and E(SiMe(3))(3) afforded for E = P a high yield of the trimer [H(2)AlP(SiMe(3))(2)](3) (1), while for E = As a monomeric base-stabilized adduct [H(2)AlAs(SiMe(3))(2)].NMe(3) (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 [H(2)AlAs(SiMe(3))(2)] stabilized by coordination of NMe(3) at the Al site. Pyrolysis of 1 at 450 degrees C promoted further dehydrosilylation and yielded a product which by XRD spectroscopy showed the onset of AlP crystallinity while at 950 degrees C afforded nanocrystalline AlP with 5 nm average particle size. Pyrolysis of 2 at 450 degrees 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 pathway via dehydrosilylation was accompanied by other decomposition side reactions and retention of some contaminant residues.
Janik
Jerzy F.
JF
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514.
Wells
Richard L.
RL
White
Peter S.
PS