Stepwise selective reaction of two N-cyanoethyl groups attached to C-racemic tetraaza macrocyclic nickel(II) and copper(II) complexes in aqueous solutions

► [Ni(C-racemic-L2)(OAc)]+ is hydrolyzed to yield [Ni(C-racemic-L3)]2+ at pH <6. ► [Ni(C-racemic-L3)]2+ undergoes hydrolysis or C-N bond cleavage in basic aqueous solution. ► The reactivity of [Ni(C-meso-L2)]2+ is different from that of [Ni(C-racemic-L2)(OAc)]+.