Dehydrosilylation reactions in diethyl ether between H3Al . NMe3 and E(SiMe3)(3) afforded for E = P a high yield of the trimer [H2AlP(SiMe3)(2)](3) (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 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 AIP with 5 nm average particle size. Pyrolysis of 2 at 450 OC 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.