title: Aluminum compounds containing eta1- and/or eta5-bidentate dianionic pyrrolyl-methylamide ligands.
abstract: A series of dialuminum compounds have been synthesized and their reactivity and application for lactide polymerization have been studied. The reaction of AlH3 x NMe3 with [C4H3NH(2-CH2NHtBu)] in diethyl ether generated a dimeric aluminum hydride compound, [[[C4H3N(2-CH2NtBu)]AlH]2] (1). The structure of 1 was confirmed by spectroscopy of a deuterated analogue of 1 with an Al--D function. Direct treatment of [C4H3NH(2-CH2NHtBu)] with LiAlH4 in diethyl ether resulted in colorless crystals of [[Li[micro-eta1:eta5-C4H3N(2-CH2NtBu)]2Al]2] (2) in 80 % yield after recrystallization from a toluene solution. The micro-eta1:eta5-pyrrolyl protons exhibit high-field shifts at delta=5.73, 6.15, and 6.72 comparable to a similar eta5-bonding mode in the literature. Treatment of 1 with 1 equiv acetone oxime or acetone in dichloromethane gave [[[C4H3N(2-CH2NtBu)]Al[varkappaO,varkappaN-(ON==CMe2)]]2] (3) and [[[C4H3N(2-CH2NtBu)]Al(O--CHMe2)]2] (4) in 67 % and 60 % yield, respectively. Compounds 1-4 have been characterized by X-ray diffractometry and were used as catalysts for epsilon-caprolactone polymerization.
authors.affiliation: Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan.
authors.forename: Ya-Chi
authors.initials: YC
authors.lastname: Chen
authors.forename: Che-Yu
authors.initials: CY
authors.lastname: Lin
authors.forename: Chun-Yin
authors.initials: CY
authors.lastname: Li
authors.forename: Jui-Hsien
authors.initials: JH
authors.lastname: Huang
authors.forename: Ling-Chueh
authors.initials: LC
authors.lastname: Chang
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Lee