Synthesis and properties of the first [Au(dien)(N-heterocycle)]3+ compounds.

Novel Au(III)(dien)(N-heterocycle) compounds, including the first Au(III)N3(N-purine) examples, are reported. The acidity of the dien ligand is affected by the nature of the fourth ligand as a leaving group. The metal center of [Au(dien)(N-heterocycle)](3+) compounds was shown to be more stable to reduction than when Cl(-) is present, with consequences for reactivity with biomolecules: specifically, significant enhancement of π-π-stacking interactions with tryptophan relative to isostructural and isoelectronic platinum(II) and palladium(II) compounds.