ELECTRONIC-SPECTRUM AND PHOTOREACTIVITY OF DICHLORO(1,5-CYCLOOCTADIENE)-PALLADIUM(II)

The complex Pd-II(1,5-COD)Cl-2 (1,5-COD = 1,5-cyclooctadiene) shows a long-wavelength ligand-to-metal charge transfer (LMCT) absorption at l ambda(max) = 342 nm. It is suggested that LMCT excitation generates a COD radical cation and (PdCl2-)-Cl-I in the primary photochemical step . In acetonitrile, a back-electron transfer takes place that leads to the transformation of 1,5-COD to its 1,3-isomer and a solvated Pd(II) complex. In ethanol, the COD radical cation and Pd-I are reduced by th e solvent, which is oxidized to acetaldehyde. Metallic palladium is fo rmed as a colloid. (C) 1998 Elsevier Science S.A. All rights reserved.