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2 species. The variable-temperature, multinuclear NMR study of the Me 2 AlH/ P(SiMe 3 ) 3 system indicated adduct formation at -90 °C and subsequent conversion to cyclic oligomeric [Me 2 AlP(SiMe 3 ) 2 ] n [Me 2 AlH] m species at -80 °C that ultimately produced [Me 2 -AlP(SiMe 3 ) 2 ] 2 . The reactivity of Bu i 2 AlH toward P(SiMe 3 ) 3 and HP(SiMe 3 ) 2 is much slower then that of Me 2 AlH. In the Bu i 2 AlH/HP(SiMe 3 ) 2 system, H 2 elimination is favored and [Bu i 2 -AlP(SiMe 3 ) 2 ] 2 and Bu i 2 AlP(SiMe 2 ) 2 ‚Bu i 2 AlP(H)SiMe 3 are formed. An X-ray structure analysis of [Bu i 2 AlP(SiMe 3 ) 2 ] 2 establishes the planarity of the (AlP) 2 core.Recently we reported the reactivity of Me 2 AlH with HP(SiMe 3 ) 2 , 26 wherein the preferred mode of reactivity is HSiMe 3 sas opposed to H 2 selimination. Transpho-

Me2AlH and Bui 2AlH were reacted with a series of nine aminoarsines, Me2AsR (R = NMe2, NPrn 2, NPri 2, NBun 2, NBui 2, NC4H8, NC5H10, NC6H12, and N(C2H4)2NMe), in C6D6 at room temperature, and the reactions were monitored by 1H and 13C NMR spectroscopy. The relative rates for initial As−N bond cleavage and final product formation were dependent on the steric requirements of the alkyl groups attached to aluminum and nitrogen in the starting materials. Overall rates were slower with Bui 2AlH than with Me2AlH for a given aminoarsine. For most of the reactions, the predominant Al-containing products were the dimeric aminoalane compounds, [Me2AlR]2 and [Bui 2AlR]2. Although Al−N bond formation was the prefered mode of reaction, Al−As bond formation was also observed when the bulky Pri and Bui aminoarsine derivatives were used. The [Bui 2AlR]2 compounds were synthesized independently by the reaction of Bui 2AlH and the respective amine or, in the case of [Bui 2AlNBui 2]2, by the reaction of Bui 2AlCl and LiNBui 2. X-ray crystal structures were determined for the compounds [Me2AlNC6H12]2, [Me2AlN(C2H4)2NMe]2, [Bui 2AlNMe2]2, and [Bui 2AlN(C2H4)2NMe]2. All of the compounds have planar Al2N2 rings with the exception of [Bui 2AlN(C2H4)2NMe]2, which displays a puckered Al2N2 ring.

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