Luminescent gold(I) macrocycles with diphosphine and 4,4′-bipyridyl ligands

The complexes [{–Ph2P(CH2)nPPh2AuNC5H4C5H4NAu–}x]2x+ [CF3CO2−]2x (n = 1–6) were prepared as colourless, air-stable solids by reaction of silver trifluoroacetate with the corresponding precursor complex [(CH2)n(Ph2PAuCl)2], and subsequent treatment of the products [(CH2)n(Ph2PAuO2CCF3)2] with 4,4′-bipyridyl. The complexes are suggested to exist in solution as an equilibrium mixture of linear oligomers and cyclic complexes. When n = 1, 3 or 5 the cationic complexes were shown to exist as 26-, 30- and 34-membered macrocyclic rings respectively; only when n = 1 are there significant intramolecular Au⋯Au contacts of 3.106(1) and 3.084(1) Å. Some of the complexes are strongly emissive at room temperature in solution and in the solid state.