Diphosphines and pyrazole/pyrazolate-type ligands as building blocks in luminescent Au(I) complexes

A series of gold(I) complexes containing diphenylphosphine bridging ligands, dppm, dppe, dpephos, dbfphos and biphep and co-ligands of the type pyrazole have been synthesized. The X-ray crystal structures of [Au2(μ-dpephos)(μ-pz2CH3)][PF6], [Au2(μ-dbfphos)(μ-pz2CH3)][PF6], and of the starting compound [Au2Cl2(μ-biphep)] indicate that the structural and stoichiometric characteristics of the new complexes depend on the diphosphine ligand. The three complexes show Au⋯Au contacts between 3.27 Å and 3.30 Å, with that of the biphep compound being the shortest. Digold (I)-diphosphine derivatives with a bridging pyrazolate ligand are obtained in all cases, except when [Au2Cl2(μ-biphep)] is used as starting material. Surprisingly, in this case, two monodentate neutral pyrazole ligands are attached to the gold atoms. The new complexes are luminescent in the solid state at 77 K and in solution both at room temperature and 77 K. Low energy emission bands related to the presence of Au⋯Au interactions have been identified in some of the compounds in the solid state and/or in solution.

Luminescent Au(I) complexes based on pyrazole/pyrazolate and diphosphine ligands have been synthesized. The relationships between the structural and luminescent properties of the compounds have been studied, thus offering an insight on how these could be tuned for future applications.Figure optionsDownload as PowerPoint slideHighlights
► Luminescent Au(I) complexes with pyrazole/pyrazolate ligands have been synthesized.
► Relationships between structural and luminescent properties have been established.
► The study indicates how such properties could be tuned for applications.