2-Amino-5-picoline N-oxide complexes formed from various copper(II) salts

Copper(II) complexes with 2-amino-5-picoline N-oxide (2am5PicO = L), CuL₄X₂(X = ClO₄, BF₄, and NO₃), CuL₂X₂ (X = Cl, Br) and CuLX₂ (X = Cl) have been isolated and characterized using spectral methods (i.e. IR, UV-vis and ESR). Coordination occurs via the N-oxide oxygen exclusively with the amine functional group showing only slight tendency to involve itself in hydrogen bonding to the anions. The halide complexes involve the halide ions in the coordination spheres while the polyatomic anions are not bound directly to copper. The latter compounds have monomeric, 4-coordinate CuO₄ chromophores while the former solids are apparently polymeric. Evidence for N-oxide bridging ligands in the CuL₂X₂ solids and halogen bridging in the CuLX₂ solid is presented.