Oxazolone copper(I) complexes inspired by the methanobactin active site

► Bidentate oxazolone ligands reminiscent of the chelating {NS} motif of methanobactin. ► Copper(I) complexes with bridging thioether groups and a very rare central {Cu2S2} diamond core. ► NMR spectroscopic clues about the isomerization of oxazolone derivatives with exocyclic enethioether substituent.