Three CuI complexes of diimine-bearing macrocyclic ligands are described. Reaction of CuI with macrocycles of different ring size gives rise to differing degrees of aggregation of (CuI)_n in the solid state. X-Ray diffraction studies reveal that whereas macrocycles with smaller ring sizes give rise to simple mononuclear CuI diimine complexes, a macrocycle of larger ring size affords a dinuclear (CuI)₂ moiety, encompassed within the ligand ring. Thus, the macrocycle can be seen to determine the extent of CuI aggregation in the solid state.