PHOTOCHEMISTRY OF THE IRCL62- COMPLEX IN METHANOL MATRICES

Low-temperature spectrophotometry and electron spin resonance (ESR) we re used to study the IrCl62- photochemistry in methanol matrices froze n at 77 K. Photoreaction gives rise to the absorption band of an IrCl3 6- complex with a maximum at 215 nm and to a new band with a maximum a t 287 nm that is unobservable during IrCl62- photolysis in solutions a t room temperature. The appearance of this new band is assigned to the formation of a weak complex between the . CH2OH radical and IrCl63- i on (i.e. a IrCl23-.... CH2OH radical complex). The irradiation of meth anol matrix with IrCl62- gives rise to the . CH2OH radical signal in t he ESR spectrum with additional splitting which can be attributed to t he partial delocalization of spin density from radical to the IrCl63- complex and the appearance of hyperfine splitting (HFS) on the iridium nucleus. When the matrix is heated to 115 K the IrCl63-.... CH2OH com plex disappears. (C) 1997 Elsevier Science S.A.