Effect of the Nitrogen Substituent on the Reactions of Alane towards Imino‐ and Aminophenols: Generation of a Dinuclear Aluminoxane

AlH 3 · NEtMe 2 reacts with salicylaldimines 3,5‐ t Bu 2 –2‐(OH)C 6 H 2 CH=NR [R = C 6 F 5 ( 1a ), 2,6‐Me 2 C 6 H 3 ( 1b ); 0.5 equiv.] to give the bisphenoxido‐amido‐imino compounds [Al{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH=NR}{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH 2 –NR}] [R = C 6 F 5 ( 4a ), 2,6‐Me 2 C 6 H 3 ( 4b )]. When the substituent on the nitrogen is 2,6‐Me 2 C 6 H 3 , it is possible to isolate the bis(phenoxido‐imino) hydride [AlH{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH=N–2,6‐Me 2 C 6 H 3 } 2 ] ( 3 ) if the reaction is performed at low temperature. Compound 4a is converted in wet toluene at room temperature readily and quantitatively into the aluminoxane [(Al{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH=NC 6 F 5 }{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH 2 –NHC 6 F 5 }) 2 O] ( 5 ). The mononuclear bis(phenoxido‐amino) hydrides [AlH{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH 2 –NHR} 2 ] [R = 2,6‐Me 2 C 6 H 3 ( 6b ), t Bu ( 6c )] are obtained by treatment of AlH 3 · NEtMe 2 with aminophenols 3,5‐ t Bu 2 –2‐(OH)C 6 H 2 CH 2 –NHR [R = 2,6‐Me 2 C 6 H 3 ( 2b ), t Bu ( 2c ); 0.5 equiv.] in toluene at –78 °C. Compound 6b evolves into [Al{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH 2 –NH–2,6‐Me 2 C 6 H 3 }{3,5‐ t Bu 2 –2‐(O)C 6 H 2 CH 2 –N–2,6‐Me 2 C 6 H 3 }] ( 7 ), which can also be generated by the direct reaction of 2b with AlH 3 · NEtMe 2 (0.5 equiv.) at room temperature. The molecular structures of 4b and 5 have been determined by X‐ray diffraction analysis.