Synthesis, structures, and magnetic behavior of a series of copper(II) azide polymers of Cu_4 building clusters and isolation of a new hemiaminal ether as the metal complex

摘要

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~(II)_4 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.