Solvent-assisted spontaneous resolution of a 16-membered ring containing gold(I) showing short Au...Au aurophilic interaction and a figure-eight conformation.

The achiral 4,6-bis(diphenylphosphino) phenoxazine (nixantphos) ligand was used to synthesize a gold(I) complex, Au2(nixantphos)22, containing a 16-membered Au2(nixantphos)2 cationic ring in a chiral figure-eight conformation. The single crystal X-ray diffraction analysis of Au2(nixantphos)22.3MeOH.H2O (1) and Au2(nixantphos)22.4MeCN (2) revealed a solvent-assisted spontaneous resolution of the Au2(nixantphos)22 complex. By changing the nature of the solvent, homochiral hydrogen bonded helices (1) and heterochiral hydrogen bonded monomers (2) were obtained. Multinuclear NMR spectroscopy showed the evidence of chemical exchange phenomenon related to the interconversion of the enantiomeric skeletons of the 16-membered macrocycle in solution. The existence of the Au...Au aurophilic interaction was confirmed by the analysis of the spin-system in the (31)P NMR spectrum.