Olefin Rearrangement Resulting from the Gas-Phase KrF Laser Photolysis of Cr(CO)6

Article abstract of DOI:10.1021/ja00365a013

We have found that irradiation of Cr(CO)6-1-butene mixtures in the gas phase with a KrF laser (248 nm) results in the efficient (yield ca. 0.2) isomerisation of 1-butene to 2-butene, in marked contrast to results in solution.The primary photochemical yield is independent of 1-butene pressure and of Cr(CO)6 pressure over wide pressure ranges.Secondary photochemical processes are also found, the importance of which depends upon 1-butene pressure.We also report yields of species Cr(CO)m(PF3)6-m resulting from irradiation of Cr(CO)6-PF3 mixtures at 248 nm.At high dilution -3>, we find relative yields of 0.10, 0.14, 0.73, and 0.03 for Cr(CO)2(PF3)4, Cr(CO)3(PF3)3, Cr(CO)4(PF3)2, and Cr(CO)5PF3, respectively.These results suggest a high degree of transormation following optical excitation at 248 nm.We present a resonable kinetic model to explain the observed isomerization of butene in which a primary photofragment, probably Cr(CO)3 or Cr(CO)2, is the active species.