Abstract The reaction of NiCl2·6H2O with one equivalent hemilabile diaminodiamide ligandN,N′-bis(β-carbamoylethyl)1,2-diaminocyclohexane (1) gave a pale blue compound [Ni(C12H24N4O2)(H2O)2]2·3H2O·4Cl (2). With more than one equivalent ligands, 2 was transformed to a yellow species [Ni(C12H22N4O2)]·3H2O (3) by the Ni–O to Ni–N bond rearrangement at two amide sites of the complex. The color change could