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Photochemical elimination of dihydrogen is a key route to carbon-hydrogen bond activation, particularly by half-sandwich rhodium, osmium and iridium compounds. The photochemical method is able to obtain kinetic data by laser flash photolysis. Studies of complexes of the type RU(Rsub2PCHsub2CHsub2PRsub2)sub2Hsub2 (R = Me, Et, Ph, Csub2Fsub5), showed that each undergoes dihydrogen photodissociation, yielding 16-electron Ru(Rsub2PCHsub2CHsub2Prsub2)sub2 fragrments, characterized by a multiband UV/vis spectra. The photochemistry of RU(PPsub3)Hsub2 and Os(PPsub3)Hsub2 by preparative and in situ NMR is explored.

Fe(dmpe)2 was characterized in solution at room temperature, and the kinetics of its reactions with substrates, including CO, H2, alkanes and arenes, were examined using laser flash photolysis analyses with UV/vis and infrared detection to examine the transient and matrix photochemistry of Fe(dmpe)2He(dmpe=Me2PCH2CH2PMe2). The rates of oxidative addition of arenes, alkenes and alkanes were directly measured. Fe(dmpe)2 is radically different from its ruthenium analogue in relation to its reactivity and its spectroscopic characteristics.

The photolysis of the ruthenium(II) complex with bisdimethylphosphinoethane, Ru(dmpe)2H2, in low-temperature matrix and in solution generates the Ru(dmpe)2 species. When dihydrogen is present in the matrix or in the absence of other ligands in solution, selective irradiation regenerates Ru(dmpe)2H2. The reactions of Ru(dmpe)2 with H2 or CO shows that it exists as a singlet. Ru(dmpe)2 is also very reactive with a number of ligands, the presence of which shifts the photoreaction equilibrium. The chemical behavior and spectra of Ru(dmpe)2 differ from those of Fe(dmpe)2 but are closer to those of Ru(CO)2(PMe3)2.

Examines the photochemistry of a complex compound. Performance of preparative, nuclear magnetic resonance and time-resolved studies; Synthesis of the dinitrogen complex; Determination of kinetic isotope effects.