RESUMO
Laser flash photolysis was used to study the nature and reactions of intermediates for a novel photochromic system consisting of perfluorodiphenyl disulfide (F(5)C(6)SSC(6)F(5) = (SBF)(2)) and a flat di(mercaptoquinolinato)Ni(II) (Ni(SC(6)H(3)NC(3)H(3))(2) = Ni(SR)(2)) complex in benzene solutions. Under UV-radiation disulfide dissociates into two sulfur-containing radicals (F(5)C(6)SË = ËSBF) that vanish in recombination. In the presence of the Ni(SR)(2) complex recombination competes with radical coordination yielding the radical (SBFË)Ni(SR)(2) complex. This complex has an absorption band in the visible region and disappears in the second-order reaction when radical-complex recombines into dimer ((RS)(2)Ni(SBF)(2)Ni(SR)(2)). Subsequent dimer dissociation into initial disulfide and two Ni(SR)(2) complexes completes the photochromic cycle.
