Mechanism of (&mgr;-H)(&mgr;-alkenyl)Re(2)(CO)(8) Formation in 350 nm Flash Irradiations of Re(2)(CO)(10)

The mechanism of (&mgr;-H)(&mgr;-alkenyl)Re(2)(CO)(8) formation upon UV irradiations of Re(2)(CO)(10) in presence of olefin (styrene, trans-stilbene, 4-methyl-1-cyclohexane, and ethylene) was investigated by laser flash photolyses. Such photoproducts result from reactions of the olefin with eq-Re(2)(CO)(9). No reactions of Re(CO)(5) leading to hydride alkenyl products were observed. Dependences of the reaction rate on olefin concentration and solvent revealed an additional intermediate formed after the addition of the olefin to eq-Re(2)(CO)(9) and before the appearance of the &mgr;-hydrido-&mgr;-alkenyl products.