Coordination structures of Cu ions in the mixed-solvent system of formamide and ammonium formate

Michihiro Miyake, Shin Nagahara, Yumi Yoshikawa, Takashi Suzuki

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The coordination structures of the Cu ions in the mixed solvent system of HCONH2-HCOONH4 at room temperature and 100 °C have been investigated using the EXAFS (extended X-ray absorption fine structure) method for the Cu K-edge, together with visible absorption spectrum analyses and ion-exchange experiments. The Cu ions, which are divalent, CuII, at room temperature, are reduced to univalence, CuI, by heating with HCOO- ions, ca. 80% of CuII ions are transformed into CuI, ions at 100 °C. In the mixed solvent system, it was found that CuII ions form neutral [Cu(HCOO)2(HCONH2)4] octahedra, distorted by the Jahn-Teller effect, with four short Cu-O bond lengths of ca. 1.97 Å and two long Cu-O bond lengths of ca. 2.82 Å at room temperature, and CuI ions form cationic [Cu(HCONH2)3]+ plane triangles with three Cu-O bond lengths of ca. 1.90 Å at 100 °C. The transition of the coordination structures occurs reversibly in the mixed solvent system as a function of the temperature.

Original languageEnglish
Pages (from-to)1721-1727
Number of pages7
JournalJournal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
Volume85
Issue number11
DOIs
Publication statusPublished - Dec 1 1989
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

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