Iron(III) and Zinc(II) calixarene complexes: Synthesis, structural studies, and use as procatalysts for ε-caprolactone polymerization

Arbaoui, Abdessamad; Redshaw, Carl; Elsegood, Mark R. J.; Wright, Victoria E.; Yoshizawa, Akina; Yamato, Takehiko

Abstract

Treatment of the heterobimetallic iron(II) alkoxides [(THF)MFe(OtBu)3]2 with p-tert-butylcalix[4]areneH4 (L1H4) affords the oxo-bridged diiron(III) complexes {Fe[M(NCMe)x]2L1}2(μ-O), M=Na, x=2 1⋅8(CH3CN), M= K, x=3 2⋅3.5(CH3CN); similar use of p-tert-butylcalix[6]areneH6 (L2H6) afforded [{Fe2(μ-O)Na2(OH2)(NCMe)2L2}2][{Fe2(μ-O)Na(OH2)(NCMe)6L2}2]2-[Na(NCMe)5]22+3⋅9.46(CH3CN) and [{Fe2(μ-O)L2(K(NCMe)2)2}2] 4⋅10.8(MeCN), respectively. In the case of 4, a minor product {(L22Fe8O8)[K(NCMe)1.5K(H2O)(NCMe)2.5]2} 5⋅6(CH3CN), which is comprised of chains of (L22Fe8O8) clusters bridged by K/MeCN fragments, is also isolated. Use of p-tert-butylcalix[8]areneH8 (L3H8) and two equivalents of [(THF)KFe(OtBu)3]2 affords [(K2(μ-NCCH3)4(μ-OH2))2(Fe2(μ-O)L3H2)2(CH3CN)2] 6⋅9(CH3CN). In the case of p-tert-butyltetrahomodioxacalix[6]areneH6 (L4H6), reaction with [(THF)MFe(OtBu)3]2 (two equivalents) leads to isolation of the pseudoisomorphic complexes [M2(CH3CN)4L4Fe2(μ-O)].4CH3CN M=Na 7⋅4(CH3CN), M=K 8⋅2(CH3CN); similar use of p-tert-butylhexahomotrioxacalix[3]areneH3 (L5H3) led to [Na2Fe2(μ-OH)2(L5)2(CH3CN)4] 9⋅2(CH2Cl2). The complex [L4(ZnEt)4Zn2(CH3CN)4(μ-OEt)2], 10⋅2(CH3CN), isolated from the reaction of L4H6 and ZnEt2 is also reported. Complexes 1–10 are structurally characterized (partially in the case of 4) and screened (not 5) as catalysts for the ring opening polymerization of ε-caprolactone.

Citation

Arbaoui, A., Redshaw, C., Elsegood, M. R. J., Wright, V. E., Yoshizawa, A., & Yamato, T. (2010). Iron(III) and Zinc(II) calixarene complexes: Synthesis, structural studies, and use as procatalysts for ε-caprolactone polymerization. Chemistry - An Asian Journal, 5(3), 621-633. https://doi.org/10.1002/asia.200900514

• Journal Article Type: Article
• Acceptance Date: Sep 30, 2009
• Online Publication Date: Jan 27, 2010
• Publication Date: Feb 22, 2010
• Deposit Date: Nov 13, 2014
• Journal: Chemistry-An Asian Journal
• Print ISSN: 1861-4728
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 3
• Pages: 621-633
• DOI: https://doi.org/10.1002/asia.200900514
• Keywords: Calixarenes; Crystal growth; Heterometallic complexes; Iron; Polymerization
• Public URL: https://hull-repository.worktribe.com/output/468221
• Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1002/asia.200900514
• Contract Date: Nov 13, 2014