pH-dependent transfer hydrogenation of water-soluble carbonyl compounds with [Cp*IrIII(H2O)3]2+ (Cp* = η5C5Me5) as a catalyst precursor and HCOONa as a hydrogen donor in water

Seiji Ogo, Nobuyuki Makihara, Yoshihito Watanabe

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148 Citations (Scopus)

Abstract

This paper reports a pH-dependent hydrogenation of water-soluble carbonyl compounds by hydrogen transfer from HCOONa as a hydrogen source (transfer hydrogenation) promoted by [Cp*IrIII(H2O)3]2+ (1, Cp* = η5-C5Me5) as a catalyst precursor in water. Complex 1 has been characterized by X-ray structure analysis, 1H NMR, and potentiometric titration experiments. The active catalyst, a dinuclear μ-hydride complex [(Cp+IrIII)2(μ-H)(μ-OH)(μ-HCOO)]+ (2), has been isolated and characterized by 1H NMR, IR, and electrospray ionization mass spectrometry (ESI-MS). The rate of this transfer hydrogenation shows a sharp maximum at pH 3.2 because the active catalyst 2 is generated from the reaction of 1 with HCOONa at pH 3.2 in the highest yield. The series of the carbonyl compounds consists of a straight chain aldehyde (n-butyraldehyde), a cyclic aldehyde (cyclopropanecarboxaldehyde), a ketone (2-butanone), an aldehyde-acid (glyoxylic acid), and a keto-acid (pyruvic acid). Products were determined by 1H NMR and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). A possible mechanism for this transfer hydrogenation is proposed.

Original languageEnglish
Pages (from-to)5470-5474
Number of pages5
JournalOrganometallics
Volume18
Issue number26
DOIs
Publication statusPublished - Dec 20 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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