Synthesis, magnetic properties, and electronic spectra of mixed ligand bis(β-diketonato)chromium(III) complexes with a chelated nitronyl nitroxide radical: X-ray structure of [Cr(dpm)2(NIT2py)]PF6

Yasunori Tsukahara, Atsushi Iino, Takafumi Yoshida, Takayoshi Suzuki, Sumio Kaizaki

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

A new series of nine nitronyl nitroxide Cr(III) complexes with various β-diketonates, [Cr(β-diketonato)2(NIT2py)]PF6, have been synthesized where NIT2py is 2-(2′-(pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-3-oxide- 1-oxyl, and their structures, magnetic and optical properties have been examined. X-Ray analysis of [Cr(dpm)2(NIT2py)]PF6 (monoclinic, space group P21/a, a = 13.960(4), b = 31.19(1), c = 13.940(4), Z = 4) demonstrated that NIT2py coordinated to Cr(III) as a bidentate six-membered chelate. Variable-temperature magnetic susceptibility measurements indicated the antiferromagnetic interaction between Cr(III) and NIT2py with a variety of the magnetic coupling constant J values for these complexes. From the variable temperature or solvent dependent UV-vis spectra and MCD, and/or the resonance Raman spectra of the bis(β-diketonato)(NIT2py) Cr(III) complexes, the absorption components centered around 13.3 × 103 cm-1 were assigned to the formally spin-forbidden d-d transition within the t2g subshell associated with the intensity enhancement and the newly appeared vibronic bands around (16.0-18.0) × 103 cm-1 were due to the metal-ligand charge transfer [t2g-SOMO(φ*) MLCT] transitions. The change of their spectroscopic characteristics with varying the β-diketonato ligands is discussed in connection with the antiferromagnetic coupling constant J values on the basis of the exchange mechanism along with the coligand effect. The luminescence spectra which show a large Stokes shift suggest the antiferromagnetic interaction in the lowest excited states originates from the 2E or 2T1 level of the Cr(III) moiety.

Original languageEnglish
Pages (from-to)181-187
Number of pages7
JournalJournal of the Chemical Society, Dalton Transactions
Issue number2
DOIs
Publication statusPublished - Jan 1 2002
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)

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