Direct formation of formic acid from carbon dioxide and dihydrogen using the [{Rh(cod)Cl}₂]–Ph₂P(CH₂)₄PPh₂catalyst system

Formic acid, isolable as sodium formate from the reaction mixture, is produced directly from hydrogen and carbon dioxide with yields up to 1150 moles per mole of rhodium using a homogeneous catalyst formed in situ from [{Rh(cod)Cl}2] and Ph2P(CH2)4PPh2; the precious metal is recovered during work-up in a catalytically active form.