The N-functionalized macrocyclic ligand 2,13-bis(1-naphthalenylmethyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo-(14,4,0 1.18 ,0 7.12 )docosane (L 3 ) and its copper(II) complex were prepared. The crystal structure of [Cu(L 3 )](ClO 4 ) 2 ·2CH 3 CN was determined by single-crystal X-ray diffraction at 150 K. The copper atom, which lies on an inversion centre, has a square planar arrangement and the complex adopts a stable trans-III configuration. The longer dis-