Hydrogen Generation from Water upon CpMn(CO)3 Irradiation in a Hexane/Water Biphasic System

Photolysis of CpMn(CO)(3) in a hexane/water biphasic system has been shown to generate hydrogen peroxide and hydrogen in 40-50% yield. Photolysis of the title compound results in loss of a CO ligand followed by coordination of a water molecule. The initially formed CpMn(CO)(2)(H2O) intermediate was detected using time-resolved IR spectroscopy. The cyclopentadiene (CpH) monomer is generated as the major product, formed by the transfer of an H atom from the coordinated H2O solvent to the Cp ring. A simple mechanism for H-2 generation is proposed on the basis of deuteration studies which demonstrate the production of D-2 and CpD upon photolysis of CpMn(CO)(3) in a hexane/D2O biphasic system.