Aluminium complexes containing bidentate and symmetrical tridentate pincer type pyrrolyl ligands: Synthesis, reactions and ring opening polymerization

Wen Yen Huang, Sheng Jie Chuang, Nien Tsu Chunag, Ching Sheng Hsiao, Amitabha Datta, Shau Jiun Chen, Ching Han Hu, Jui Hsien Huang*, Ting Yu Lee, Chia Her Lin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

A series of aluminium derivatives containing substituted bidentate and symmetrical tridentate pyrrolyl ligands, [C4H3NH(2-CH 2NHtBu)] and [C4H2NH(2,5-CH 2NHtBu)2], in toluene or diethyl ether were synthesized. Their reactivity and application for the ring opening polymerization of ε-caprolactone have been investigated. The reaction of AlMe3 with one equiv. of [C4H3NH(2-CH 2NHtBu)] in toluene at room temperature affords [C 4H3N(2-CH2NHtBu)]AlMe2 (1) in 70% yield by elimination of one equiv. of methane. Interestingly, while reacting AlMe3 with one equiv. of [C4H3NH(2- CH2NHtBu)] in toluene at 0°C followed by refluxing at 100°C, [{C4H3N(2-CH2NtBu)}AlMe] 2 (2) has been isolated via fractional recrystalliztion in 30% yield. Similarly, reacting AlMe3 with two equiv. of C4H 3NH(2-CH2NHtBu) generates [C4H 3N(2-CH2NHtBu)]2AlMe (3) in a moderate yield. Furthermore, complex 1 can be transformed to an aluminium alkoxide derivative, [C4H3N(2-CH2NH tBu)][OC6H2(-2,6-tBu 2-4-Me)]AlMe (4) by reacting 1 with one equiv. of HOC 6H2(-2,6-tBu2-4-Me) in toluene via the elimination of one equiv. of methane. The reaction of AlR3 with one equiv. of [C4H2NH(2,5-CH2NH tBu)2] in toluene at room temperature affords [C 4H2N(2,5-CH2NHtBu) 2]AlR2 (5, R = Me; 6, R = Et) in moderate yield. Surprisingly, from the reaction of two equiv. of [C4H 2NH(2,5-CH2NHtBu)2] with LiAlH 4 in diethyl ether at 0°C, a novel complex, [C4H 2N(2-CH2NtBu)(5-CH2NH tBu)]2AlLi (7) has been isolated after repeating re-crystallization. Furthermore, reacting one equiv. of C4H 2NH(2,5-CH2NHtBu)2 with AlH 3·NMe3 in diethyl ether generates an aluminium dihydride complex, [C4H2N(2,5-CH2NH tBu)2]AlH2 (8), in high yield. Additionally, treating 8 with one equiv. of HOC6H2(-2,6- tBu2-4-Me) in methylene chloride produces [C 4H2N(2,5-CH2NHtBu) 2][OC6H2(-2,6-tBu 2-4-Me)]AlH (9) with the elimination of one equiv. of H2. The aluminium alkoxide complex 4 shows moderate reactivity toward the ring opening polymerization of ε-caprolatone in toluene.

Original languageEnglish
Pages (from-to)7423-7433
Number of pages11
JournalDalton Transactions
Volume40
Issue number28
DOIs
Publication statusPublished - 2011 Jul 28
Externally publishedYes

ASJC Scopus subject areas

  • Inorganic Chemistry

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