Synthesis and characterisation of tetramethylpiperidinyloxide (TEMPO) complexes of group 13 metal hydrides

Abstract

Attempts have been made to prepare low oxidation state group 13 hydride complexes by reacting the metal trihydride–Lewis base adducts, [MH₃(quin)] (quin = quinuclidine, M = Al, Ga or In), with reducing or hydrogen abstraction reagents. The 1 : 1 reactions with 2,2′,6,6′-tetramethylpiperidinyl oxide (TEMPO) yield the first structurally characterised nitroxide–group 13 hydride complexes, [MH₂(quin)(TEMPO)] (M = Al or Ga). The 2 : 1 reaction with [AlH₃(quin)] affords [AlH(quin)(TEMPO)₂] which has also been structurally authenticated. The mechanisms of these reactions are discussed.