Synthesis and electro-spectroelectrochemistry of ferrocenyl naphthaquinones

Yucel B., SANLI B., SOYLEMEZ H., Yılmaz İ.

TETRAHEDRON, vol.67, no.7, pp.1406-1421, 2011 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 67 Issue: 7
  • Publication Date: 2011
  • Doi Number: 10.1016/j.tet.2010.12.057
  • Journal Name: TETRAHEDRON
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1406-1421
  • Keywords: Electron donor acceptor, Electrochemisty, Spectroelectrochemistry, Electron transfer, Ferrocene, Naphthaquinones, Thermal rearrangement, GENERAL REGIOSPECIFIC SYNTHESIS, ELECTROCHEMICAL REDUCTION, QUINONE-HYDROQUINONE, CYCLIC VOLTAMMETRY, REDOX BEHAVIOR, P-BENZOQUINONE, DERIVATIVES, COMPLEXES, FLUORENE, PHTHALOCYANINE
  • Istanbul Technical University Affiliated: Yes

Abstract

A practical approach to ferrocenyl naphthaquinone derivatives involving thermal rearrangement of variously substituted 4-aryl-4-hydroxycyclobutenones was described. The reaction of 3-ferrocenyl-4-isopropoxy-3-cyclobutene-1,2-dione with different aryl lithiums gave the corresponding 4-aryl-4-hydroxycyclobutenones, which were heated in p-xylene at reflux open to the air to yield ferrocenyl naphthaquinones. The redox chemistry of the ferrocenyl naphthaquinones was studied by electrochemical and in situ spectroelectrochemical techniques in CH2Cl2 solution and in CH3CN solution with water, weak and strong acidic additives. Ferrocenyl naphthaquinones displayed reversible two reduction processes involving semiquinone radical anion (Fc-snq(center dot-)), dianion (Fc-nq(2-)) species and a one-electron oxidation process based on the ferrocenium/ferrocene (Fc(+)-nq/Fc-nq) couple in CH2Cl2. The redox reaction mechanism of the ferrocenyl naphthaquinones in the presence of the additives proceeded via hydrogen bonding or proton-coupled electron transfer. Effects of the substituents on the reduction potentials and intramolecular charge-transfer bands of ferrocenyl naphthaquinones were also discussed. (C) 2011 Elsevier Ltd. All rights reserved.