Preparation, crystal structure and magnetic properties of di-2-pyridylamine (dpa) copper(II) complexes [Cu(dpa)(N3)2]n and [Cu2(dpa)2(NCO)4]

The preparation, crystal structures and magnetic properties of two copper(II) complexes with di-2-pyridylamine (dpa) as end-cap ligand and azide (1) and cyanate (2) as bridging groups, [Cu(dpa)(N3)2]n (1) and [Cu2(dpa)2(NCO)4] (2), are reported. Compound 1 consists of uniform chains of copper(II) ions bridged by single μ-1,1-azido groups whereas that of compound 2 is made up of centrosymmetric dicopper(II) units with double μ-1,1-N-cyanate bridges, the other two cyanate groups acting as terminal ligands. The copper atoms in 1 and 2 are five-coordinated with two nitrogen atoms of a bidentate dpa ligand (1 and 2), one nitrogen atom from a terminally bound azide (1)/cyanate (2) and two other nitrogens from two azide (1)/cyanate (2) bridges building intermediate square pyramidal/trigonal bipyramidal (1) and distorted square pyramidal (2) surroundings. The values of the copper–copper separation through the double end-on azido (1) and cyanato (2) bridges are 3.8556(4) and 3.5154(5) Å, respectively. Variable-temperature magnetic susceptibility measurements show the occurrence of weak magnetic interactions in both complexes being antiferromagnetic in 1 [J = −4.60 cm−1, the Hamiltonian is defined as Hˆ=-J∑iSˆi·Sˆi+1] and ferromagnetic in 2 [J = +3.14 cm−1 with Hˆ=-JSˆ1·Sˆ2]. The magnitude and nature of these magnetic interactions are discussed in the light of the respectives structures and they are compared with those reported for related systems.