Barriers to rotation of axially coordinated imidazole ligands in nonplanar meso-Tetraalkylporphyrinato-cobalt(III) complexes

Takashi Saitoh, Takahisa Ikeue, Yoshiki Ohgo, Mikio Nakamura

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Dynamic NMR study of a series of meso-[Co(TRP)(L)2]Cl, where R is an alkyl group and L is a substituted imidazole, has been carried out. While the complexes with unhindered imidazole show no splitting of die signals, those with bulky imidazoles exhibit change in line shape, indicating the hindered imidazole rotation. The activation free energy increases as R and/or L become bulkier. Based on the red-shifted Soret and Q bands in the UV-Visible and the downfield shifted imidazole protons in the 1H NMR spectra of these complexes as compared with the meso unsubstituted complexes, it is concluded that the deformation of the porphyrin ring slows down the rate of rotation of the coordinated ligand.

Original languageEnglish
Pages (from-to)12487-12496
Number of pages10
JournalTetrahedron
Volume53
Issue number37
DOIs
Publication statusPublished - 1997 Sep 1

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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