Fluorescence from Samarium(II) Iodide and Its Electron Transfer Quenching: Dynamics of the Reaction of Benzyl Radicals with Sm(II).
The luminescence from SmI(2) in THF can be readily quenched by a variety of electron acceptors. In the case of organohalides, the reaction is quite fast; for example, for dichloromethane the rate constant is 2.7 x 10(8) M(-)(1) s(-)(1). Electron transfer leads to halide loss and formation of the carbon-centered radical. In the case of benzyl chloride, the benzyl radicals produced can be readily detected using laser flash photolysis techniques. This electron-transfer reaction has been used as a source of benzyl radicals in order to determine the rate constant for their reaction with SmI(2); the value obtained is (5.3 +/- 1.4) x 10(7) M(-)(1) s(-)(1) in THF at room temperature. The effect of HMPA on the spectroscopic properties of SmI(2) has also been examined.
Skene
W. G.
WG
Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Scaiano
J. C.
JC
Cozens
F. L.
FL