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Syntheses, Molecular Structures, and Spectroscopy of Gold(III) Dithiolate Complexes
M. Adnan Mansour1, Rene J. Lachicotte, Henry J. Gysling
1NSF-Science and Technology Center for Photoinduced Charge Transfer, Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, and Imaging Research and Advanced Development, Eastman Kodak Company, Rochester, New York 14650-2109.
Inorganic Chemistry
|October 24, 2001
Summary
Two new gold(III) dithiolate complexes were synthesized and characterized. These complexes exhibit unique electronic properties and structural arrangements, differing from related platinum(II) compounds.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Materials Science
Background:
- Gold(III) complexes are of interest for their unique electronic and photophysical properties.
- Dithiolate ligands offer versatile coordination modes and influence metal center reactivity.
- Understanding structure-property relationships in gold complexes is crucial for developing new functional materials.
Purpose of the Study:
- To synthesize and structurally characterize two novel gold(III) dithiolate complexes.
- To investigate the electronic and photophysical properties of these complexes.
- To compare their properties with related platinum(II) complexes and explore structure-property correlations.
Main Methods:
- Synthesis of [Au(dbbpy)(tdt)]PF(6) and Au(eta(2)-C,N-ppy)(tdt) complexes.
- X-ray crystallography for detailed structural determination.
- UV-Vis absorption spectroscopy to study electronic transitions.
- Electrochemical methods (oxidation and reduction potentials) to assess reactivity.
- Luminescence spectroscopy to evaluate emissive properties.
Main Results:
- Both gold(III) complexes were successfully synthesized and structurally characterized, revealing approximately square planar coordination.
- Low-energy absorption bands were observed, assigned to charge-transfer-to-diimine transitions, occurring at higher energy than in analogous Pt(II) complexes.
- Neither Au(III) complex was emissive, unlike their dichloride precursors which showed luminescence from an intraligand pi-pi excited state.
- Electrochemical studies indicated differences in oxidation and reduction potentials between the cationic and neutral gold(III) complexes.
- X-ray data revealed a structural trans effect in Au(eta(2)-C,N-ppy)(tdt) and intermolecular Au-Au interactions in the solid state for both complexes.
Conclusions:
- The synthesized gold(III) dithiolate complexes possess distinct electronic and structural features compared to related platinum(II) systems.
- The lack of luminescence in the Au(III) dithiolate complexes is attributed to efficient non-radiative decay pathways.
- The study provides valuable insights into the coordination chemistry and photophysics of gold(III) dithiolate complexes, relevant for materials design.