Reaction of primary amines with N-ethynyl pendant arms attached to macrocyclic nickel(II) and copper(II) complexes: Formation of the complexes with pendant imine group(s)

•Reaction of primary amines with N-CH2CCH pendant arms attached to tetraaza macrocyclic nickel(II) and copper(II) complexes.•Synthesis of macrocyclic nickel(II) and copper(II) complexes bearing coordinated imine pendant arm(s).•Effects of the central metal on the reaction of N-CH2CCH pendant arms.

The two N-CH2CCH pendant arms of [NiL1]2+ (L1 = 2,13-bis(N-propargyl)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[16.4.0.07.12]docosane) react readily with benzyl amine or n-propylamine to produce the trans-octahedral complexes, [NiL2]2+ and [NiL4]2+, bearing two N-CH2C(NCH2C6H5)CH3 or two N-CH2C(NCH2CH2CH3)CH3 pendant arms. [CuL1]2+, however, reacts with the primary amines to form a square-pyramidal complex [CuL3]2+ or [CuL5]2+ bearing one N-CH2C(NCH2C6H5)CH3 or N-CH2C(NCH2CH2CH3)CH3 pendant arm as well as one N-CH2CCH group under similar experimental conditions. The pendant imine group of the nickel(II) or copper(II) complexes of L2–L5 is involved in coordination and is inert against hydrolysis, even in aqueous 1.0 M HClO4 or 1.0 M NaOH solutions.

Graphical abstractThe N-CH2CCH pendant arms of [NiL1]2+ react readily with primary amines (RNH2) to produce 1 bearing two N-CH2C(NR)CH3 pendant arms. On the other hand, the reaction of [CuL1]2+ with RNH2 produces 2 bearing both N-CH2C(NR)CH3 and N-CH2CCH groups.Figure optionsDownload full-size imageDownload as PowerPoint slide