Synthesis of a Trigold Monocation: An Isolobal Analogue of [H₃]⁺

Isolobal and isolatable: A triangular [L3Au3]+ ion, bearing N-heterocyclic carbene ligands (L), is crystallographically characterized (see structure; Au yellow, C gray, N blue). Density functional theory suggests full valence delocalization among the gold atoms, with the HOMO composed largely of gold 6s orbitals and the LUMO comprising a degenerate pair. This orbital picture is analogous to that of [H3]+.