Preparation, crystal structures, and spectroscopic properties of cobalt(III) complexes bearing 2,4-pentanedionate (acac-) and 2-cyanoethylphosphines: Trans-[Co(acac)2{P(CH2CH 2CN)nPh3-n}]BF4 (n = 1-3)

Keiko Kihara, Syohei Yamaguchi, Yasuo Kawahata, Masakazu Kita, Takayoshi Suzuki, Yukinari Sunatsuki, Masaaki Kojima, Kazuo Kashiwabara

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A series of cobalt(III) complexes containing 2-cyanoethylphosphines, [Co(acac)2{P(CH2CH2CN)nPh 3-n}2]BF4 {acac = 2,4-pentanedionate; n = 1 (1), 2 (2), and 3 (3)} have been prepared, and their molecular and crystal structures have been determined. The X-ray diffraction study revealed that these complexes are the trans isomers in the crystals. The Co-P bond lengths are little affected by the number of 2-cyanoethyl substituents on the P atom, which is consistent with a small change of the σ-donicity among these phosphines. The trans configuration of these complexes is maintained in solution, as revealed by 1H NMR spectroscopy. The 2-cyanoethylphosphines could not form stable cis-isomers of [Co(acac) 2{P(CH2CH2CN)nPh3- n}2]+, like the corresponding methylphosphines (PMenPh3-n). This fact probably results from a strong electron-withdrawing property of a terminal cyano group of phosphine substituent. In the UV-Vis absorption spectra of complexes 1-3, the LMCT transition band is observed in the range of 20 500-24 000 cm-1, which is comparable to the analogous PMenPh3-n complexes, but their intensity is characteristically weaker than that of the corresponding PMenPh3-n complexes.

Original languageEnglish
Pages (from-to)111-114
Number of pages4
Publication statusPublished - Jan 1 2014



  • 2-Cyanoethylphosphine
  • Cobalt(III) complexes
  • Crystal structures: LMCT transition

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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