Highly efficient dehydrogenation of formic acid in aqueous solution catalysed by an easily available water-soluble iridium(iii) dihydride.
The new water-soluble cis-mer-[IrH2Cl(mtppms)3] (mtppms = monosulfonated triphenylphosphine) was employed as a catalyst for selective decomposition of formic acid to H2 + CO2 in aqueous solution at T = 30-100 °C. The easily synthesized compound showed high catalytic activity (TOF up to 298 000 h(-1)) and could be reused several times with no loss of activity (total TON = 67 650). A sharp maximum in the reaction rate was observed at pH = 3.75; its coincidence with the pKa of formic acid shows that both H(+) or HCOOH and HCOO(-) play important roles in the reaction mechanism.
Hungarian Academy of Sciences, Research Group of Homogeneous Catalysis and Reaction Mechanisms, P.O. Box 400, Debrecen, H-4002 Hungary. papp.gabor@science.unideb.hu.
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