摘要
The reaction of 2-phenoxyethanol with AlX <sub>3</sub> affords a five-coordinated dimeric product [(μ-OCH <sub>2</sub> CH <sub>2</sub> OPh)AlX <sub>2</sub> ] <sub>2</sub> (1, X=Cl; 2, X=Br) in high yields. However, the reaction of 2-phenoxyethanol with Al(Bu <sup>i</sup> ) <sub>3</sub> yields a four-coordinated dimeric product [(μ-O(CH <sub>2</sub> ) <sub>2</sub> OPh)Al(Bu <sup>i</sup> ) <sub>2</sub> ] <sub>2</sub> (3). A mixture, [(μ-O(CH <sub>2</sub> ) <sub>2</sub> OPh)Al(Et) <sub>0.75</sub> (Cl) <sub>1.25</sub> ] <sub>2</sub> (4) is obtained from the reaction of 2-phenoxyethanol with one equivalent of Et <sub>2</sub> AlCl. The reaction of 2-methoxybenzyl alcohol with AlR <sub>3</sub> gives a semi-pentacoordinated dimeric product [(μ-OCH <sub>2</sub> C <sub>6</sub> H <sub>4</sub> OMe)AlR <sub>2</sub> ] <sub>2</sub> (5, R=Me; 6, X=Bu <sup>i</sup> ) in high yields. Crystal structure studies of these compounds reveal that the distance between Al and the phenoxy oxygen or the methoxy oxygen is 3>6>5≫4>1~2. Although both the electronic and steric effect influence the nature of the O,O′-bifunctional ligand chelating on the aluminum center to generate a five- or four-coordinated aluminum, the electronic effect is considered to play a major role. The interaction of aluminum and ethereal oxygen can be monitored by <sup>13</sup> C-NMR spectroscopic studies. © 1999 Elsevier Science S.A.