Synthesis, Characterization, and Luminescence Studies of Discrete Polynuclear Gold(I) Sulfido and Selenido Complexes with Intramolecular Aurophilic Contacts

The synthesis, characterization, and photophysical and photochemical properties of a family of high-nuclearity gold(l) chalcogenides, specifically, the gold(I) sulfido and selenido complexes containing different bridging diphosphine ligands with nuclearities of ten ([Au-10{mu-Ph2PN(R)PPh2}(4)(mu(3)-E)(4))(2+)) and six ([Au-6{mu-Ph2PN(R)PPh2}(3)(mu(3)-E)(2)](2+)), are reported. The X-ray crystal structures of the complex cations of Au-10 and Au-6 are found to be propeller-like structures and distorted cubane- structures, respectively, with the presence of short intramolecular gold-gold distances. The complexes show intense green and/or orange phosphorescence upon photoexcitation in the solid state and in solution at ambient and low temperature. The emission properties are found to be strongly dependent on the nuclearities and the chalcogenido ligands, but are rather insensitive to the substituents on the bis(diphenylphosphino)amines. The emissions are tentatively assigned to originate from the excited states derived from the phosphine-centered intraligand (IL) transition or metal-centered (ds/dp) mixed with ligand-to-metal metal charge transfer (LMMCT) (E -> Au) transition. The photochemical properties of the complexes were also studied by transient absorption spectroscopy.