Ligand and medium controlled photochemistry of iron and ruthenium mixed-ligand complexes: prospecting for versatile systems

Selected Fe and Ru systems, whose photochemical behaviour is sensitive to n umerous parameters, are presented. These systems, containing multiple speci es in equilibrium, are versatile enough to be adapted to special tasks and may also be used to model the phenomena and mechanisms occurring in nature. The role of various parameters is analysed and principal emphasis is given to the ligand sphere influence on the nature of the excited state and ther eby on the photochemical mode. This is crucial in the case of Fe(II) comple xes of the type [Fe(CN)(5)L](n-), whereas in the carbolyl-cyclopentadienyl complexes, represented by [cpRu(CO)(2)](2), the nature of the excited state is of less importance than for pentacyanoferrates(II). The photochemistry of the carbonyl-cyclopentadienyl complexes is more susceptible to the impac t of the medium and the role of the secondary processes is more significant . (C) 2000 Elsevier Science S.A. All rights reserved.