Emissive Annular Digold(I) Compounds Containing Diphosphine and Dithiolate Ligands

Molecular structures of three emissive annular digold compounds Au₂(dmpm)(dtc)]Cl (dmpm = Me₂PCH₂PMe_2,dtc = S₂CNEt₂), 1 , Au₂(dppm)(dtc)]PF₆, (dppm = Ph₂PCH₂PPh₂),₂,and Au₂(dppe)(dtc)]-(PF₂) (dppe = Ph₂P(CH₂)₂PPh₂), 3, were determined. All three compounds are dimetallacycles having two gold atoms bridged by a dithiolate ligand and a diphosphine ligand, the geometry around each gold atom being almost linear. All the dimetal lacy die rings are slightly distorted from planarity with intramolecular Au-Au distances shorter than 3.0 Å. Compound 1 forms a polymeric chain through intermolecular Au-Au contacts (3.061 ? 3.135 Å). Compound 2 forms a tetramer through intermolecular Au-Au interactions (Au-Au distances ranging from 3.086 to 3.222 ). Compound 3 is monomeric. All of the compounds luminesce at 77 K in the solid state. Emissions originating from ³LMCT from dtc ligand to Au excited states are assigned. The emission maxima of 1 ? 3 are at 541,535 and 520 nm respectively and are blue shifted as the number of Au-Au interactions is decreased.