Reaction of Al(tBu)3 with [R2Al{µ-O(CH2)nNMe2}]2: dependence on the extent of intra-molecular Al  · 4;· 4;·  N coordination

Reaction of Al(tBu)3 with (tBu)3Al[O(H)CH2CH2CH2NMe2] yielded the Lewis acid–base complex [(tBu)2Al{µ-OCH2CH2CH2N(Me)2Al(tBu)3}]2 1. Compound 1 is also formed directly when 2 equivalents of Al(tBu)3 reacts with 1 equivalent of [(tBu)2Al(µ-OCH2CH2CH2NMe2)]2. In contrast, the reaction of 2 equivalents of Al(tBu)3 with 1 equivalent of [Me2Al(µ-OCH2CH2NMe2)]2 yielded Me2Al(µ-OCH2CH2NMe2)Al(tBu)3 2. The molecular structure of compound 2 shows the AlMe2 moiety chelate bound to the anionic bidentate ligand, while the Al(tBu)3 unit is bonded to the anionic terminus of the ligand. The formation of compound 1 is proposed to occur via the tert-butyl analog of compound 2, i.e., (tBu)2Al(µ-OCH2CH2CH2NMe2)Al(tBu)3, which is unstable due to significant tBu  · 4;· 4;·  tBu inter-ligand interactions. The implications of the differences in products is discussed with respect to the extent of intra-molecular Al  · 4;· 4;·  N coordination in compounds of the general formula [R2Al{µ-O(CH2)nNMe2}]2.