Photocrystallographic observation of halide-bridged intermediates in halogen photoeliminations. Academic Article uri icon


  • Polynuclear transition metal complexes, which frequently constitute the active sites of both biological and chemical catalysts, provide access to unique chemical transformations that are derived from metal-metal cooperation. Reductive elimination via ligand-bridged binuclear intermediates from bimetallic cores is one mechanism by which metals may cooperate during catalysis. We have established families of Rh2 complexes that participate in HX-splitting photocatalysis in which metal-metal cooperation is credited with the ability to achieve multielectron photochemical reactions in preference to single-electron transformations. Nanosecond-resolved transient absorption spectroscopy, steady-state photocrystallography, and computational modeling have allowed direct observation and characterization of Cl-bridged intermediates (intramolecular analogues of classical ligand-bridged intermediates in binuclear eliminations) in halogen elimination reactions. On the basis of these observations, a new class of Rh2 complexes, supported by CO ligands, has been prepared, allowing for the isolation and independent characterization of the proposed halide-bridged intermediates. Direct observation of halide-bridged structures establishes binuclear reductive elimination as a viable mechanism for photogenerating energetic bonds.

published proceedings

  • J Am Chem Soc

author list (cited authors)

  • Powers, D. C., Anderson, B. L., Hwang, S. J., Powers, T. M., Prez, L. M., Hall, M. B., ... Nocera, D. G.

publication date

  • January 1, 2014 11:11 AM