Monomeric Alanes: Synthesis, Structure, and Thermolysis of MesAl(H)N(SiMe(3))(2) and a One-Pot Synthetic Route to Mes(2)AlH (Mes = -C(6)H(2)-2,4,6-t-Bu(3)).
The reaction of (MesAlH(2))(2) (Mes = -C(6)H(2)-2,4,6-t-Bu(3)) with HN(SiMe(3))(2) affords the monomeric amidoarylalane MesAl(H)N(SiMe(3))(2), 1. This product can also be synthesized by the reaction of [MesAlH(2)](2) with LiN(SiMe(3))(2), which, in addition, yields the byproducts LiAlH(2){N(SiMe(3))(2)}(2), 3, and MesH. Thermolysis of 1 at 175-180 degrees C affords three different the related and the imide [MesAlN(SiMe(3))](n)(), 5. In addition, the previously reported monomeric alane Mes(2)AlH was synthesized in ca. 70% yield by a one-pot reaction between LiMes (generated in situ) and AlH(3).NMe(3). All products were spectroscopically characterized, and the structure of 1 was determined by X-ray crystallography. The Al-N distance (1.819(2) Å) in 1 is relatively long. However, it has a substantial, 18.5 kcal mol(-)(1), Al-N rotation barrier which is attributed to steric congestion rather than Al-N pi bonding.
Wehmschulte
Rudolf J.
RJ
Department of Chemistry, University of California, Davis, California 95616.
Power
Philip P.
PP