PLATINUM(II) BIS(BETA-DIKETONATES) AS PHOTOACTIVATED HYDROSILATION CATALYSTS

Irradiation of platinum(II) bis(beta-diketonates) in the presence of h ydrosilanes and olefins results in olefin hydrosilation. The initial r ate of hydrosilation is dependent upon the choice of beta-diketonate l igand, hydrosilane, and olefin. Formation of an active catalyst requir es the presence of either triethylsilane or triethylvinylsilane during a brief period of irradiation. Addition of the second reactant result s in hydrosilation without further irradiation. Substantial inhibition of hydrosilation is observed when dibenzo[a,e]cyclooctatetraene is ad ded following irradiation and prior to addition of the second reactant , but not when mercury is added following irradiation, These results i ndicate that the active form of the photogenerated catalyst is homogen eous rather than heterogeneous. Correlation of hydrosilation reactivit y with the spectroscopic changes which occur during irradiation sugges ts that the primary photoproduct is not catalytically active and that a secondary photochemical reaction results in the loss of one of the t wo beta-diketonate ligands and the formation of the active catalyst.