Studies of the Ligand
Effect on the Synthesis of Dialuminoxanes
by Various β-Diketiminato Ligands
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Abstract
Reactions of LH (L = HC[C(Me)N(2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub>)]<sub>2</sub>) with Me<sub><i>n</i></sub>AlCl<sub>3–<i>n</i></sub> in diethyl ether
afforded the adducts
LH·AlMe<sub><i>n</i></sub>(Cl)<sub>3–<i>n</i></sub> (<i>n</i> = 2, <b>3</b>; 1, <b>4</b>; 0, <b>5</b>) in good yields. Treatment of <b>3</b> at elevated temperatures in toluene resulted in LAlMeCl (<b>2</b>) by intramolecular elimination of methane. The controlled hydrolysis
of LAlMeCl (<b>2</b>) with equimolar amounts of water in the
presence of N-heterocyclic carbene (NHC) gave a mixture of [LAl(Me)]<sub>2</sub>(μ-O) (<b>7</b>) and dimeric [LAlMe(μ-OH)]<sub>2</sub> (<b>8</b>). A convenient route for the preparation
of [LAlMe(μ-OH)]<sub>2</sub> (<b>8</b>) was the NHC-assisted
controlled hydrolysis of LAlMeI (<b>9</b>). Stepwise hydrolysis
of LAlH<sub>2</sub> (<b>11</b>) gave dialuminoxane hydride [LAl(H)]<sub>2</sub>(μ-O) (<b>12</b>) and dialuminoxane hydroxide
[LAl(OH)]<sub>2</sub>(μ-O) (<b>13</b>), respectively.
Anhydrous treatment of LAlCl<sub>2</sub> (<b>1</b>) or LAlMeCl
(<b>2</b>) with Ag<sub>2</sub>O afforded chlorinated dialuminoxane
[LAl(Cl)]<sub>2</sub>(μ-O) (<b>14</b>) and [LAl(Me)]<sub>2</sub>(μ-O) (<b>7</b>), respectively
