Kinetic study of the complex formation of boric and boronic acids with mono- and diprotonated ligands

Hideaki Ito, Yoko Kono, Akinori Machida, Yoko Mitsumoto, Kenji Omori, Noriko Nakamura, Yuichi Kondo, Koji Ishihara*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


The complex formation reactions of boric and boronic acids (RB(OH)2: R=OH, n-Bu, Ph, and m-NO2Ph) with 4-isopropyltropolone (Hipt) and chromotropic acid (H2cht2-) have been studied kinetically at various pH. The reactions of H2ipt+ with boronic acids were faster than those of Hipt by a factor of 1.5-11, and fully deprotonated ipt- also reacted with m-NO2PhB(OH)2, but slower than Hipt. The tetrahedral m-NO2PhB(OH)3- ion did not react with Hipt. Reaction routes for the complexation of boric acid with chromotropic acid could not be specified because of the unexpected problem of proton ambiguity. Mechanism for the reactions of boronic acids with bidentate ligands was discussed in terms of rate determining chelate ring closure. It was concluded that at least one proton is necessary for the OH- in the tetrahedral intermediates to be eliminated smoothly as water, and a doubly hydrogen-bonded intermediate was proposed for the reactions with diprotic ligands.

Original languageEnglish
Pages (from-to)28-36
Number of pages9
JournalInorganica Chimica Acta
Publication statusPublished - 2003 Feb 20


  • Boric acid
  • Boronic acid
  • Complex formation kinetics

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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