Synthesis, magnetic properties and MCD spectra of a four coordinate copper(II) complex with two chelated phenolate-substituted imino nitroxides

Hironori Kanda, Yasuo Narumi, Yuko Hosokoshi, Takayoshi Suzuki, Satoshi Kawata, Koichi Kindo, Katsuya Inoue, Sumio Kaizaki

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A reaction of Cu(II) nitrate and 4,4,5,5-tetramethyl-2-(2-hydroxophenyl) imidazolin-1-oxyl (IM2PhOH) with potassium methoxide in methanol gave a homoleptic bis(imino nitroxide) complex of [Cu(IM2PhO)2] (1). The single-crystal X-ray analysis of 1 showed that the imino nitroxide anion, IM2PhO-, chelated to a CuII ion via an imino-N and a phenoxide-O atoms to form a six-membered chelate ring. The coordination geometry around the Cu(II) ion was a distorted square-planar polygon; the dihedral angle between the two coordination planes, each of which was defined by Cu and two ligating atoms of IM2PhO-, was 40.81°. The temperature dependences of the magnetic susceptibility and the EPR spectra of 1 indicate that the magnetic interaction between Cu(II) and the imino nitroxide is ferromagnetic, while there is a moderate antiferromagnetic interaction between two coordinated imino nitroxides. A balance between these opposite interactions attains the lowest molecular doublet spin-state in 1. The variable temperature magnetic circular dichroism (MCD) spectrum of the complex 1 also showed two negative components with a large C term, which may be due to the charge-transfer (CT) transition originated from the d orbital to the SOMO π* orbital in the spin-coupled IM2PhO- radicals; resulting in the largely split doublet excited states with the spin singlet and triplet d8 configurations.

Original languageEnglish
Pages (from-to)3125-3133
Number of pages9
JournalInorganica Chimica Acta
Issue number11
Publication statusPublished - Aug 5 2004
Externally publishedYes



  • Cu(II) complex
  • EPR
  • Imino nitroxide radical
  • Magnetic interaction
  • MCD

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

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