Four new neutral copper azido polymers, [Cu 4(N 3) 8(L 1)2] n (1), [Cu 4(N 3) 8(L 2)2] n (2), [Cu 4(N 3) 8(L 3)2] n (3) and [Cu9(N3)18(L 4)4]n (4) [L 1-4 are formed in situ by reacting pyridine-2-carboxaldehyde with 2-[2-(methylamino)ethyl]pyridine (mapy, L 1), N,N-dimethylethylenediamine (N,N-dmen, L 2), N,Ndiethylethylenediamine (N,N-deen, L 3) and N,N,2,2- tetramethylpropanediamine (N,N,2,2-tmpn, L 4)], have been synthesized by using 0.5 mol equiv of the chelating tridentate ligands with Cu- (NO 3) 2 33H 2O and an excess of NaN 3. Single-crystal X-ray structures show that the basic unit of these complexes, especially 1-3, contains very similar Cu II4 building blocks. The overall structure of 3 is two-dimensional, while the other three complexes are one-dimensional in nature.Complex 1 represents a unique example containing hemiaminal ether arrested by copper(II). Complexes 1 and 2 have a rare bridging azido pathway: both end-on and end-to-end bridging azides between a pair of Cu II centers. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in all four complexes. Density functional theory calculations (B3LYP functional) have been performed on complexes 1-3 to provide a qualitative theoretical interpretation of their overall ferromagnetic behavior. {\textcopyright} 2011 American Chemical Society.