Kinetics of the photooxidation of tris(bipyridine)iron(II) in chloroform

In chloroform/acetonitrile solution, [Fe(bpy)(3)](2+), bpy = 2,2'-bipyridine, reacts under 254 nm irradiation to yield Hbpy(+) and [FeCl4]. The reaction rate is faster the lower the concentration of [Fe(bpy)(3)](2+). The reaction proceeds predominantly through light absorption by chloroform, creating KCl and (CCl3)-C-., radicals, both of which participate in the reaction. A lesser part of the reaction is initiated through light absorption by the tris(bipyridine) complex. The variation of the reaction rate with light intensity and on the fraction of light absorbed by the solvent and the metal complex is between a square root and a linear dependence, and is consistent with a mechanism passing through a [Fe(bpy)(3)Cl](2+) intermediate, in which one bipyridine is presumably monodentate. (C) 1999 Elsevier Science S.A. All rights reserved.