Excimer and Exciplex Formation in Gold(I) Complexes Preconditioned by Aurophilic Interactions

Autor: Helgard G. Raubenheimer, Hubert Schmidbaur
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Angewandte Chemie (International Ed. in English)
ISSN: 1521-3773
1433-7851
Popis: Excimers and exciplexes are defined as assemblies of atoms or molecules A/A′ where interatomic/intermolecular bonding appears only in excited states such as [A 2]* (for excimers) and [AA′]* (for exciplexes). Their formation has become widely known because of their role in gas‐phase laser technologies, but their significance in general chemistry terms has been given little attention. Recent investigations in gold chemistry have opened up a new field of excimer and exciplex chemistry that relies largely on the preorganization of gold(I) compounds (electronic configuration AuI(5d10)) through aurophilic contacts. In the corresponding excimers, a new type of Au⋅⋅⋅Au bonding arises, with bond energies and lengths approaching those of ground‐state Au−Au bonds between metal atoms in the Au0(5d106s1) and AuII(5d9) configurations. Excimer formation gives rise to a broad range of photophysical effects, for which some of the relaxation dynamics have recently been clarified. Excimers have also been shown to play an important role in photoredox binuclear gold catalysis.
Bond formation through excitation: Linear, two‐coordinate gold(I) complexes are known to aggregate side‐on through aurophilic interactions. The resulting weak Au–Au contacts are strengthened upon UV irradiation as evidenced by a shortening of the intermetallic distance and the vibrational and electronic absorption and emission characteristics of the resulting excimers. The changes in the redox potentials make [AuI−AuI]* excimers useful intermediates in photoredox catalysis.
Databáze: OpenAIRE
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