Photophysical features of the M-2(CO)(10), M = Mn and Re, solution photochemistry

In the UV photolysis of M-2(CO)(10), M = Mn or Re, flash photochemical meth ods were used for the determination of the primary product, i.e., nonacarbo nyl (M-2(CO)(9)) and pentacarbonyl (M(CO)(5)) quantum yields. The quantum y ield based action spectra are very metal dependent and indicative of differ ent mechanisms for the Re and Mn photochemistry. In the figure, the action spectra for the Re decacarbonyl photoproducts. phi(P) for Re(CO)(5) and phi (N) for Re-2(CO)(9), are superimposed with the absorption spectrum. The res ults in the photochemistry of Re-2(CO)(10) suggest that the upper electroni c states, i.e., populated by irradiating below 340 nm, produce some Re(CO)( 5).