This award in the Inorganic, Bioinorganic, and Organometallic Chemistry Program provides continued support for research on metal-metal interactions by Dr. Dennis L. Lichtenberger of the Chemistry Department, University of Arizona. Systems under investigation contain quadruple and triple metal-metal bonds, metal-metal configurations beyond occupation of the anti-bonding delta orbital, and non-bonding and weakly-associated through-space and through-ligand metal-metal interactions. The metal-metal complexes contain a variety of bridging and non-bridging ligands and represent a broad range of electron-donating and electron-withdrawing effects associated with key structural perturbations. Complexes with both weak and strong ligands coordinated to the axial position are also included. High-resolution HeI/HeII valence and high precision X-ray core photoelectron spectroscopy will be used to study both gas phase and condensed species. The project includes further development of instrumental capabilities. Metal-metal interactions contribute to the structure, stability, and reactivity of many species and influence important chemical, catalytic, and materials processes. Unique instrumentation will be developed to provide detailed electronic structure information on these interactions
