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

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

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

Treatment of the heterobimetallic iron(II) alkoxides [(THF)MFe(OtBu) 3]2 with p-tert-butylcalix[4]areneH4 (L 1H4) 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 (L2H 6) afforded [{Fe2(μ-O)Na2(OH 2)(NCMe)2L2}2][{Fe 2(μ-O)Na(OH2)(NCMe)6L2} 2]2-[Na(NCMe)5]22+ 3·9.46(CH3CN) and [{Fe2(μ-O)L 2(K(NCMe)2)2}2] 4·10.8(MeCN), respectively. In the case of 4, a minor product {(L2 2Fe8O8)[K(NCMe)1.5K(H 2O)(NCMe)2.5]2} 5·6(CH3CN), which is comprised of chains of (L22Fe8O 8) 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 [(K 2(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 (L 4H6), reaction with [(THF)MFe(OtBu)3] 2 (two equivalents) leads to isolation of the pseudoisomorphic complexes [M2(CH3CN)4L4Fe 2(μ-O)].4CH3CN M=Na 7·4(CH3CN), M=K 8·2(CH3CN); similar use of p-tert-butylhexahomotrioxacalix[3] areneH3 (L5H3) led to [Na2Fe 2(μ-OH)2(L5)2(CH 3CN)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.

Original languageEnglish
Pages (from-to)621-633
Number of pages13
JournalChemistry - An Asian Journal
Volume5
Issue number3
DOIs
Publication statusPublished - Mar 1 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Organic Chemistry

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