N‑Heterocyclic Carbene Ligands as Modulators of Luminescence in Three-Coordinate Gold(I) Complexes with Spectacular Quantum Yields

The first three-coordinate gold­(I) N-heterocyclic carbene (NHC) complexes have been prepared with the nido-carborane diphosphine. The complexes are brightly luminescent and present very high quantum yield values. The carbene ligand is able to modulate the energy of the emissions and, depending upon the substituent, the luminescence changes from blue to green. Theoretical calculations corroborate that the emissions are phosphorescence and arise from charge transfer (LML′CT) transitions from nido-carborane ligand (L) to metal/ligand group “gold­(I)–NHC ligand” (ML′).