Equilibrium between CO-bridged and non-bridged forms of [(η5-C5H5]Ru(CO)2]2 and selective photoreactivity of the non-bridged form

The reaction volumes, ΔV for the equilibrium between CO-bridged and non-bridged forms of the [(η5-C5H5)Ru(CO)2]2 complex in isooctane, isopropanol and acetonitrile were determined spectrophotometrically. The values of ΔV show that an increase in pressure facilitates formation of the CO-bridged form. The effect of pressure is discussed and compared to that of temperature and solvent polarity. Selective photolysis of the non-bridged form in toluene induces the symmetrical cleavage of the Ru--Ru bond to give two [(η5-C5H5)Ru(CO)2]. radicals. EPR experiments with nitrosodurene spin trap indicate that the ruthenium organometallic radicals activate the C--H bond and abstract an H atom from toluene

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 numerous parameters, are presented. These systems, containing multiple species 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 thereby on the photochemical mode. This is crucial in the case of Fe(II) complexes of the type [Fe(CN)5L]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 impact of the medium and the role of the secondary processes is more significant

Photochemical coupling of iron redox reactions and transformation of low-molecular-weight organic matter

The photoreactions between Fe(III)/Fe(II) and low-molecular-weight organic matter (LMWOM) under solar irradiation have significant implications for many biogeochemical cycles on the Earth and for the fates of environmental pollutants. In this Perspective, we focus on several fundamental aspects of the photochemical processes that couple the redox cycling of iron species and transformation of organic substrates. The primary photoprocesses (e.g., intramolecular electron transfer or photodissociation) are first highlighted by introducing the recently disputed observations on the photolysis of ferrioxalate complexes. The effects of LMWOM and its daughter radicals on the photochemical redox cycling of iron species are discussed with special attention given to the example of Fe–malonate complexes. These processes and mechanisms would provide us some refreshed understanding of environmental photochemistry of LMWOM and the iron species and would be helpful for our assessment of photochemical decontamination of organic pollutants