Ab initio calculations of the atomic and electronic structures of Cu N and NaN (N = 2 - 22) clusters show similar growth behaviors. These can be characterized into 3 regimes: planar, layered and 3D structures. Atomic structures lead to anomalies in the even-odd alternation behavior of the second order energy difference for N = 16 and 17 in both Cu N and NaN. The effects of sp-d hybridization on the atomic and electronic structures of CuN clusters are discussed. {\textcopyright} World Scientific Publishing Company.