PFI-ZEKE SPECTROSCOPY OF COPPER-AROMATIC NITROGEN HETEROCYCLIC COMPLEXES
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Date
2004
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Ohio State University
Abstract
Single-photon pulsed field ionization-zero electron kinetic energy (PFI-ZEKE) photoelectron spectroscopy has been used to study the complexes of copper with pyridine $(C_{5}H_{5}N)$, 2,2'-bipyridine $(C_{10}H_{8}N_{2})$ and 1,10-phenanthroline $(C_{12}H_{8}N_{2})$. In all cases, adiabatic ionization potentials and Cu-ring vibrational frequencies were measured from the ZEKE spectra. Additional ring-based vibrations were observed for Cu-bipyridine and -phenanthroline. All three Cu complexes were determined to be in $C_{2v}$ symmetry with the metal atom $\sigma$ bonding to the nitrogen of pyridine or two nitrognes of the polypyridines. Since the most stable conformation of the free 2,2'-bipyridine ligand is coplanar with trans-standing nitrogens, Cu coordination has induced a ring rotation of $180^{\circ}$ to bring the two nitrogens in a cis configuration.
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Author Institution: Department of Chemistry, University of Kentucky