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Aluminum Compounds Containing η 1 ‐ and/or η 5 ‐Bidentate Dianionic Pyrrolyl–Methylamide Ligands
Author(s) -
Chen YaChi,
Lin CheYu,
Li ChunYin,
Huang JuiHsien,
Chang LingChueh,
Lee TingYu
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200800679
Subject(s) - chemistry , diethyl ether , medicinal chemistry , dichloromethane , ether , denticity , hydride , toluene , stereochemistry , crystallography , crystal structure , organic chemistry , hydrogen , solvent
A series of dialuminum compounds have been synthesized and their reactivity and application for lactide polymerization have been studied. The reaction of AlH 3 ⋅ NMe 3 with [C 4 H 3 NH(2‐CH 2 NH t Bu)] in diethyl ether generated a dimeric aluminum hydride compound, [{[C 4 H 3 N(2‐CH 2 N t Bu)]AlH} 2 ] ( 1 ). The structure of 1 was confirmed by spectroscopy of a deuterated analogue of 1 with an AlD function. Direct treatment of [C 4 H 3 NH(2‐CH 2 NH t Bu)] with LiAlH 4 in diethyl ether resulted in colorless crystals of [{Li[μ‐η 1 :η 5 ‐C 4 H 3 N(2‐CH 2 N t Bu)] 2 Al} 2 ] ( 2 ) in 80 % yield after recrystallization from a toluene solution. The μ‐η 1 :η 5 ‐pyrrolyl protons exhibit high‐field shifts at δ =5.73, 6.15, and 6.72 comparable to a similar η 5 ‐bonding mode in the literature. Treatment of 1 with 1 equiv acetone oxime or acetone in dichloromethane gave [{[C 4 H 3 N(2‐CH 2 N t Bu)]Al[ ϰO , ϰN ‐(ONCMe 2 )]} 2 ] ( 3 ) and [{[C 4 H 3 N(2‐CH 2 N t Bu)]Al(OCHMe 2 )} 2 ] ( 4 ) in 67 % and 60 % yield, respectively. Compounds 1 – 4 have been characterized by X‐ray diffractometry and were used as catalysts for ε‐caprolactone polymerization.