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Reactions of Dimeric Aluminium Hydride Compounds Containing Bidentate Dianionic Pyrrolyl Ligands and Their Applications in Ring‐Opening Polymerization of ϵ‐Caprolactone
Author(s) -
Chen YaChi,
Lin CheYu,
Huang WenYen,
Datta Amitabha,
Huang JuiHsien,
Tsai MengShiue,
Lee TingYu,
Tu ChengYi,
Hu ChingHan
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100031
Subject(s) - chemistry , dichloromethane , denticity , medicinal chemistry , dibenzoylmethane , ring opening polymerization , reactivity (psychology) , hydride , benzophenone , stereochemistry , polymerization , polymer chemistry , organic chemistry , crystal structure , metal , medicine , alternative medicine , pathology , solvent , polymer
A series of dimeric aluminium compounds containing substituted bidentate dianionic pyrrolyl ligands have been synthesized and their reactivity and application in the ring‐opening polymerization of ϵ‐caprolactone have been studied. The reactions of [{C 4 H 3 N(2‐CH 2 N t Bu)}AlH] 2 ( 1 ) with 2 equiv. of 1‐indanone and 9‐fluorenone in dichloromethane generated [{C 4 H 3 N(2‐CH 2 N t Bu)}Al(μ‐OC 9 H 9 )] 2 ( 2 ) and [{C 4 H 3 N(2‐CH 2 N t Bu)}Al{μ‐OCH(C 12 H 8 )}] 2 ( 3 ), respectively, by hydroalumination. Similarly, the reactions of 1 with 2 equiv. of 2‐cyclohexen‐1‐one, 1‐(2,4,6‐trimethylphenyl)‐1‐ethanone, benzophenone, and 1,1‐diphenylacetone in dichloromethane afforded N t Bu‐bridged dialuminium compounds 4 – 7 , [{C 4 H 3 N(2‐CH 2 N t Bu)}Al(OR)] 2 [ 4 , R = C 6 H 9 ; 5 , R = CH(Me)(C 6 H 2 ‐2,4,6‐Me 3 ); 6 , R = CHPh 2 ; 7 , R = CH(Me)(CHPh 2 )] by insertion. A similar insertion occurred when 1 was treated with 2 equiv. of 2,4‐pentandione and dibenzoylmethane in dichloromethane to yield N t Bu‐bridged dioxylate aluminium dimeric compounds 8 and 9 , respectively. The Al atoms in compounds 2 and 4 – 7 possess a distorted tetrahedral geometry whereas the Al atoms in 8 and 9 have a square‐pyramidal environment. All the compounds have been well characterized by NMR spectroscopy and compounds 2 and 4 – 9 in the solid state were subjected to X‐ray diffraction analysis. A study of the polymerization of ϵ‐caprolactone revealed that the activity of the Al complexes is largely reliant on the steric nature of the substituents of their alkoxide groups.