Two novel Cu4O4 cubanes with functionalized chelating aziridine ligands

► Isoelectronic aziridine ligands:azC2H2R2X (3: R = H, X = OH; 4: R = Me, X = NH2). ► Neutral and ionic Cu4O4 cubanes:Cu4Br4(3-H)4 (5) and [Cu4(OH)4(4)4]Br4 (7). ► Ligand 3-H acts as bridging (η1-N, μ3-O), ligand 4 as chelating ligand (η2-N,N′). ► 5 is formed from CuBr2 by HBr elimination, 7 from CuBr by redox reaction with O2/H2O. ► Complexes 5 and 7 are the first Cu4O4 cubanes with aziridine ligands.