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(I) chalcogenides, specifically,
the gold­(I) sulfido and selenido complexes containing different bridging
diphosphine ligands with nuclearities of ten ([Au10{μ-Ph2PN­(R)­PPh2}4(μ3-E)4]2+) and six ([Au6{μ-Ph2PN­(R)­PPh2}3­(μ3-E)2]2+), are reported. The X-ray crystal
structures of the complex cations of Au10 and Au6 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.