Intra- vs Intermolecular Aurophilic Contacts in Dinuclear Gold(I) Compounds: Impact on the Population of the Triplet Excited State

Two series of dinuclear gold(I) complexes that contain two Au-chromophore units (chromophore = dibenzofurane or dimethylfluorene) connected through a diphosphane bridge that differs in the flexibility and length (diphosphane = dppb for 1,4-bis(diphenylphosphino)butane, DPEphos for bis[(2-diphenylphosphino)phenyl]ether, xanthphos for 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and BiPheP for 2,2'-bis(diphenylphosphino)-1,1'-biphenyl) have been synthesized and structurally characterized. Their photophysical properties have been carefully investigated, paying attention to the role of the presence, or absence, of aurophilic contacts and their nature (intra- or intermolecular character). This analysis was permitted due to the X-ray crystallographic determination of all of the structures of the compounds discussed herein. The quantum yields of the triplet population, ϕ_T, have been calculated by nanosecond-laser flash photolysis measurements, and we could determine the main role of the character of the aurophilic contacts in the resulting ϕ_T, being especially favored in the presence of intermolecular contacts. Time-dependent density functional theory (TD-DFT) calculations support the absorption and emission assignments and the shorter distance between S₁ and the closest triplet excited state energy in the case of the compounds with a higher triplet-state population.

Gold(i)-doped films: new routes for efficient room temperature phosphorescent materials

The synthesis of four novel gold(i)-phosphane complexes coordinated to 9-phenanthrene chromophore has been carried out through the reaction of 9-phenanthreneboronic acid and the corresponding AuClPR₃ (PR₃ = PPh₃ for triphenylphosphane (1a); 1,4-bis(diphenylphosphanyl)butane or dppb (2b); bis(diphenylphosphanyl)acetylene or dppa (2c); (AuCl)₂(diphos) (diphos = bis(diphenylphosphanyl)methane or dppm (3)) sources. The X-ray crystal structures of compounds 1a and 2b show the existence of MOF-like intermolecular assemblies that contain empty inner cavities in the absence of aurophilic contacts. In contrast, the formation of a tetranuclear complex with intramolecular aurophilic interactions was evidenced for 3. Photophysical characterization indicates dual emission in all gold(i) complexes when oxygen is removed from the sample, while only fluorescence emission is recorded for the uncoordinated ligand. The introduction of the compounds within PMMA and Zeonex was assayed, and luminescent films containing gold(i) complexes where phosphorescence is the sole pathway for emission are obtained, instead of the dual emission (with significant fluorescence contribution) recorded in solution.

Dinuclear gold(i) complexes: from bonding to applications

The last two decades have seen a veritable explosion in the use of gold(i) complexes bearing N-heterocyclic carbene (NHC) and phosphine (PR₃) ligands.

Synthesis and solid-state structures of gold(i) complexes of diphosphines

A series of diphosphine bis(gold) complexes were synthesised and the importance of aurophilic interactions for their structure formation was studied.

Alkali/coinage metals – organolithium, organocuprate chemistry

Part 1 of this chapter reviews coordination compounds of the alkali metals that contain a carbon-metal bond, looking firstly at organolithiums involving simple silanes. The use of aryl, alkynyl and N-donor ligands is also discussed. Compounds of the coinage metals - copper, silver and gold - are discussed in Part 2 of the review. Discussion is broken down by metal, with copper being considered first. Compounds containing, among others, alkene, amido and phosphido ligands are discussed, along with the significant amount of work on carbene complexes. This interest in carbene complexes is also noted within the silver and gold sections that follow, with a large number of new compounds being described. Polymeric chains and networks containing silver centres have attracted considerable interest and are described, along with the luminescent properties of a selection of novel gold species. This part of the review is completed by coverage of mixed-coinage metal structures, where the systems are found to display luminescent properties. Here again, the compounds discussed contain at least one carbon-metal bond.