Two-dimensional Cu(II)/Cd(II) complexes with double bridged [(μ-EO-N₃)(μ-N-N-tetrazolate)] chains: Crystal structures, magnetic behavior and luminescence properties

Two novel two-dimensional (2D) compounds of 3-(5-tetrazolate)-N-oxide-pyridine (L) and azide, have been synthesized and characterized. They are of formula [Cu(II)(L)(N₃)]·0.5H₂O (1) and [Cd(II)(L)(N₃)·(H₂O)]·0.5H₂O (2). Both compounds 1 and 2 consist of 2D layers with similar double-bridged ((μ-EO-N₃)(μ-N-N-tetrazolate), EO = end-on) one-dimensional (1D) chains being linked by the N-oxide-pyridine ligands. However, compounds 1 and 2 crystallize in different space group (C2/c (1), P2₁/c (2)) and exhibit different coordination geometry of central metal ions (square pyramidal (1), octahedral (2)). Magnetic investigations suggest that the mixed double [(μ-EO-N₃)(μ-N-N-tetrazolate)] bridges in compound 1 transmit antiferromagnetic couplings between Cu(II) ions (J = -16.1 cm^-1 above 46 K). And also, the emission spectra of the L ligand and complex 2 were studied in the solid state at room temperature, and an obvious blue-shift was observed in complex 2 compared with the emission of the free L ligand.