Two series of Cu(II)-picolinato complexes of 1:1 and 3:2 Cu(II)-amine/picolinate namely [Cu(L 1 )(pic)]ClO 4 and [Cu 3 (L 2
, where pic = picolinate anion, L 1 = dien (diethylenetriamine), Et 2 dien (N,N-diethyldiethylenetriamine), Medpt (3,3 0 -diamino-N-methyldipropylamine), L 2 = pmedien (N,N,N 0 ,N 00 ,N 00 -pentamethyl-diethylenetriamine), TPA (tris(2-pyridylmethyl)amine), and dpt = dipropylenetriamine were synthesized and structurally characterized by electronic and IR spectroscopy. Single crystal X-ray diffraction analysis of the complex [Cu(dien)(pic)]ClO 4 (1) reveals its monomeric nature whereas for [Cu 3 (pmedien) 3 (pic) 2 (H 2 O)](ClO 4 ) 4 AE2H 2 O (4), it was shown that the complex consists of two subunits of the mononuclear [Cu(pmedien)(pic)] + and the dinuclear [Cu 2 (pmedien) 2 (pic)(H 2 O)] 3+ cations with the perchlorate as counter ions and lattice water molecules. In the mononuclear complexes of 1 and 4 the picolinato anions act as N,O-chelating ligands, whereas N,O,O 0 -picolinato bridges are observed in the dinuclear [Cu 2 (pmedien) 2 (pic)(H 2 O)] 3+ cations of 4. The aqueous visible spectra of the complexes 1-6 are consistent with five-coordinate Cu(II) species where distorted square pyramidal geometry (SP) was assigned for complexes 2-5, trigonal bipyramidal geometry (TBP) for 6 and an intermediate geometry between SP and TBP for 1.