Metal Cluster Structures and Reactivities: Computational Elucidation of Anion Photoelectron Spectra
This group investigates the bonding and gas phase chemistries of transition metal atoms, diatomics, and small clusters through a combination of experimental and computational methods. Their experiments employ anion photoelectron spectroscopy, flow tube ion-molecule chemistry, and mass spectrometry, three techniques that are combined in one unique, home-built apparatus in the Leopold laboratory. In addition, the researchers do density functional calculations to predict the geometries, vibrational frequencies, and electronic state energies of neutral and negatively charged clusters to help assign their ground and excited electronic states and the vibrational modes active in each observed photodetachment transition. These calculations can also provide information about properties not directly measurable in experiments, such as geometries, spin multiplicities, charge distributions, and electron configurations. Spectroscopic studies can also provide useful benchmarks to aid in the further development, by other researchers, of improved theoretical methods with which to treat these small but computationally challenging systems.
Current work by this group includes studies of neutral and anionic bimetallic diatomics incorporating both group 5 and 6 transition metals, which exhibit very high order multiple bonding (e.g., a formal bond order of 6 for the chromium niobium diatomic anion). They are also studying organometallic anions produced upon reaction of early transition metal atoms of the second or third transition series (such as niobium or tantalum) with simple hydrocarbons, such as ethylene or butadiene. These results can contribute to the understanding of the relationships of gas phase chemical reactivities to the metal-containing reactant's electronic and molecular structures, and can provide insights that may be useful to other researchers in the design and synthesis of improved transition metal catalysts.
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