Synthesis and Characterization of Sterically Hindered Alkylaluminum−Phosphorus and −Arsenic Compounds. X-ray Crystal Structures of (Me3ECH2)3Al·E‘(SiMe3)3(E = Si, E‘ = As; E = C, E‘ = P, As), (Me3SiCH2)2(Br)Al·P(SiMe3)3, and [(Me3SiCH2)(X)AlE(SiMe3)2]2(X = Br, E = P, As; X = Me3SiCH2, E = As)

Reaction of (Me 3 SiCH 2 ) 3 Al with E(SiMe 3 ) 3 (E = P, As) in a 1:1 mole ratio affords the Lewis acid−base adducts (Me 3 SiCH 2 ) 3 Al·P(SiMe 3 ) 3 ( 1 ) and (Me 3 SiCH 2 ) 3 Al·As(SiMe 3 ) 3 ( 2 ). Similarly, the 1:1 mole ratio reaction of (Me 3 CCH 2 ) 3 Al with E(SiMe 3 ) 3 (E = P, As) leads to the isolation of (Me 3 CCH 2 ) 3 Al·P(SiMe 3 ) 3 ( 3 ) and (Me 3 CCH 2 ) 3 Al·As(SiMe 3 ) 3 ( 4 ). The adduct (Me 3 SiCH 2 ) 2 (Br)Al·P(SiMe 3 ) 3 ( 5 ) was obtained from the 1:1 mole ratio reaction of (Me 3 SiCH 2 ) 2 AlBr with P(SiMe 3 ) 3 . The dimers [(Me 3 SiCH 2 )(Br)AlP(SiMe 3 ) 2 ] 2 ( 6 ) and [(Me 3 SiCH 2 )(Br)AlAs(SiMe 3 ) 2 ] 2 ( 7 ) were isolated as products of the lithium halide elimination reactions of (Me 3 SiCH 2 )AlBr 2 ( 10 ) with LiE(SiMe 3 ) 2 (E = P, As), while reaction of (Me 3 SiCH 2 ) 2 AlBr with these same lithium pnictide salts leads to the isolation of [(Me 3 SiCH 2 ) 2 AlP(SiMe 3 ) 2 ] 2 ( 8 ) and [(Me 3 SiCH 2 ) 2 AlAs(SiMe 3 ) 2 ] 2 ( 9 ). Various physical and spectroscopic data, including a variable-temperature NMR study of the dimeric compounds 6 − 9, are presented for the above compounds, as are the single-crystal X-ray structures of 2 − 7 and 9 .