One-dimensional copper(II) complexes containing only single end-on azido bridges: Crystal structures and magnetic properties

Two one-dimensional (1D) azido-bridged coordination polymers of formula [Cu(L¹)(μ-1,1-N₃)(N₃)]_n (1) and [Cu(L²)(μ-1,1-N₃)(N₃)]_n (2) have been synthesized and structurally characterized, and their magnetic properties have been studied, where L¹ and L² are the bidentate Schiff bases obtained from the condensation of 2-pyridylaldehyde with aniline and p-chloroaniline, respectively. Both compounds consist of 1D uniform chains in which the Cu(II) ions with a distorted square pyramidal geometry are interlinked by single end-on azido bridges in the asymmetric basal-apical fashion, and the chains are interlinked by weak C-H⋯N hydrogen bonds into two-dimensional (2D) layers. They represent the first examples of metal azido complexes containing only single end-on azido bridges. Temperature- and field-dependent magnetic analyses reveal that weak antiferromagnetic interactions are mediated by the single asymmetric bridges, with the exchange parameters being -2.2 and -3.7 cm^-1 for 1 and 2, respectively.