The copper phosphinimide complexes [Cu{μ-NPR₃}]₄ (1, R = NMe₂ and 2, R = Ph) were obtained in good yields from the reactions of Cu[Mes] (Mes = mesityl, C₆H₂Me₃-2,4,6) with the corresponding iminophosphoranes, HNPR₃. The molecular structures of 1 and 2 reveal the presence of planar eight-membered {Cu₄N₄} rings which contrasts with the saddle-shaped {M₄N₄} rings found in related metal phosphinimide complexes. According to computations, there is negligible aromaticity in the planar {Cu₄N₄} rings in 1 and 2 and the saddle shape observed in related {M₄N₄} rings is due to steric factors.