Abstract Various pyrazole-based P, N (2a–c) and N, N (3a–b) ligands have been synthesized. Using representative ligands, Ni II, Co II, Cu II, and Cu I complexes have been prepared and structurally characterized by crystallography. During complexation of Co II and Cu II salts, the phosphane part of the P, N ligand oxidized to phosphane oxide. For N, N donor ligands, a dimeric chloro-bridged Ni II complex was obtained. Ni II complex 4 is an ...