Inorganic Chemistry, Vol.47, No.6, 2049-2055, 2008
Solvent-assisted spontaneous resolution of a 16-membered ring containing gold(I) showing short Au center dot center dot center dot Au aurophilic interaction and a figure-eight conformation
The achiral 4,6-bis(diphenylphosphino) phenoxazine (nixantphos) ligand was used to synthesize a gold(l) complex, [Au-2(nixantphos)(2)](NO3)(2), Containing a 16-membered [Au-2(nixantphos)(2)](+2) cationic ring in a chiral figure-eight conformation. The single crystal X-ray diffraction analysis of [Au-2(nixantphos)(2)](NO3)(2) center dot 3MeOH center dot H2O (1) and [Au-2(nixantphos)(2)](NO3)(2) center dot 4MeCN (2) revealed a solvent-assisted spontaneous resolution of the [Au-2(nixantphos)(2)](NO3)(2) 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 center dot center dot center dot Au aurophilic interaction was confirmed by the analysis of the spin-system in the P-31 NMR spectrum.