Golden crowns: cation binding by macrocyclic gold(I) crown ether derivatives

The polyether bis(alkynes) α,ω-bis(O-propargyl)triethylene glycol and α,ω-bis(O-4-propargyloxyphenoxy)triethylene glycol reacted with [AuCl(SMe2)] in the presence of base to form the corresponding oligomeric gold(I) acetylide complexes (AuCCCH2O(CH2CH2O)3CH2CCAu)n and (AuCCCH2OC6H4O(CH2CH2O)3C6H4OCH2CCAu)n. These digold(I) diacetylide complexes reacted with diphosphine ligands to give macrocyclic digold(I) complexes of the type [Au2(μ-CC)(μ-PP)], where CC is the diacetylide and PP is a diphosphine ligand. These digold(I) complexes bind the cations Li+, Na+, K+ and Cs+, as studied by electrospray mass spectrometry.