Abstract Structures and spectroscopic properties of copper(II) compounds of the two cyclam derivatives L 1 and L 2 are reported. L 1 has four 4-cyanobenzyl N-substituents and L 2 has a fused barbiturate ring at one of the two propylene bridges. The copper(II) complexes of L 1 ([Cu(L 1)(NCCH 3)] 2+ and [Cu(L 1)(OH 2)] 2+) have trans-I configuration and are five-coordinate with extremely short axial bonds. The reaction of [(Cu(L 2)(OH 2) 2] 2+ (purple, six-coordinate, trans-III configuration) with urea and NCS − leads to a blue five-coordinate, and with urea alone to a red four-coordinate species. The CuN 4 chromophores of the three copper(II) compounds of L 2 are close to identical, and the color changes are analyzed to be due to the differences in axial interactions.