Synthesis, characterization and reactivity study of aluminum compounds incorporating bi- and tri-dentate pyrrole-piperazine ligands

Ting Chia Hu, Ming Chun Wu, Shih Sheng Wu, Ching Han Hu, Chia Her Lin, Amitabha Datta, Tzung Han Lin, Jui Hsien Huang

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Abstract

Substituted bi- and tri-dentate pyrrole-piperazine precursors, C4H3NH-[2-CH2N(CH2CH2)2NPh] (1) and C4H2NH-{2,5-[CH2N(CH2CH2)2NPh]2} (2) are synthesized and the corresponding Al derivatives are afforded systematically in moderate yield. Reacting one equivalent of 1 with AlMe3 in toluene generates an aluminum dimethyl compound, AlMe2{C4H3N-[2-CH2N(CH2CH2)2NPh]} (3) in satisfactory yield. Similarly, the reaction of two equivalents of 1 and AlMe3 affords [AlMe{C4H3N[2-CH2N(CH2CH2)2NPh]}2] (4), which on repeating recrystallization in dichloromethane produces [AlMe{C4H3N[2-CH2N(CH2CH2)2NPh]}2[NH(CH2CH2)2NPh]] (4a) in small quantity. Furthermore, reactions of 3 with one equivalent of 1,3-diphenylpropane-1,3-dione and 2,6-diisopropylphenol in toluene results in the aluminum methyl compounds, [AlMe(PhCOCHCOPh){C4H3N[2-CH2N(CH2CH2)2NPh]}] (5) and [AlMe(O-2,6-iPr2C6H3){C4H3N[2-CH2N(CH2CH2)2NPh]}] (6), respectively. Interestingly on fractional recrystallization, compound 6 affords the μ2-oxo bridged dialuminum compound, [{Al(O-2,6-iPr2C6H3){C4H3N[2-CH2N(CH2CH2)2NPh]}}2(μ-O)] (6a) while exposed to air. Additionally, the combination of the tridentate pyrrole ligand 2 and one equivalent of AlMe3 in toluene produces [AlMe2{C4H2N{2,5-[CH2N(CH2CH2)2NPh]2}}] (7). Compounds 3, 4a, 5, and 6a are subjected to X-ray diffraction analysis to ensure the geometry around the Al atom. Overall, the influences of the new pyrrole-piperazine incorporated N-donor precursors on the structural factors, reactivity with small organic molecules and the associated mechanistic details are discussed.

Original languageEnglish
Pages (from-to)16331-16339
Number of pages9
JournalRSC Advances
Volume6
Issue number20
DOIs
Publication statusPublished - 2016 Jan 1

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

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