Excited States of Gold(I) Compounds, Luminescence and Gold-Gold Bonding

It has long been established by Khan that the superoxide anion, O(2) (-), generates singlet oxygen, O(2) (1)Delta(g), during dismutation. Auranofin, gold-phosphine thiols, beta-Carotene, and metal-sulfur compounds can rapidly quench singlet O(2). The quenching of the O(2) (1)Delta(g), which exists at 7752 cm(-1) above the ground state triplet, may be due to the direct interaction of the singlet O(2) with gold(I) or may require special ligands such as those containing sulfur coordinated to the metal. Thus we have been examining the excited state behavior of gold(I) species and the mechanisms for luminescence. Luminescence is observed under various conditions, with visible emission ranging from blue to red depending on the ligands coordinated to gold(I). Triplet state emission can be found from mononuclear three coordinate Au(I) species, including species which display this behavior in aqueous solution. A description is given of the luminescent three coordinate TPA (triazaphosphaadamantane) and TPPTS (triphenylphosphine-trisulfonate) complexes, the first examples of water soluble luminescent species of gold(I).