Constrained digold(I) diaryls: syntheses, crystal structures, and photophysics

A series of di(gold(I) aryls), L(AuR)(2) (L = DPEphos, DBFphos, or Xantphos; R = 1-naphthyl, 2-naphthyl, 9-phenanthryl, or 1-pyrenyl), have been prepared. The complexes were characterized by multinuclear NMR spectroscopy, static and time-dependent optical spectroscopy, mass spectrometry, microanalysis, and X-ray crystallography. In addition, DFT calculations on model dinuclear gold complexes have been used to examine the electronic structures. Photophysical properties of the dinuclear complexes have been compared to mononuclear analogues. Low-temperature excited-state lifetimes for both the mononuclear and dinuclear complexes in toluene indicate triplet-state emission. Time-resolved DFT calculations suggest that emission originates from aryl-ligand transitions, even if the LUMO resides elsewhere.