obtained irradiating aqueous solutions (5 × 10−5 M). For mechanistic purposes and products studies irradiation has also been carried out on concentrated solutions (1 × 10−3 M) in water/acetonitrile, acetonitrile, methanol, methanol/acetonitrile, in the presence and absence of oxygen. Photoproducts, isolated by chromatographic processes, have been identified by spectroscopic means. Photochemical cleavage