Structures and magnetic properties of dicopper(II) and dinickel(II) complexes with end-on azido bridges

An asymmetric single EO azido bridged dinuclear copper(II) complex, [Cu2(dmterpy)2(μ-1,1-N3)(N3)2] · NO3 · (H2O)21 [dmterpy = 5,5″-dimethyl-2,2′:6′,2″-terpyridine], and a double EO azido bridged dinuclear nickel(II) complex, [Ni2(pbdiim)4(μ-1,1-N3)2] · 2(N3) · 6(H2O) 2 [pbdiim = 2-(2′-pyridyl)benzo[1,2-d:4,5-d′]diimidazole], have been synthesized and characterized structurally and magnetically. Compound 1 consists of a single EO azido bridged CuII dimer in which each CuII ion is five-coordinated in the form of a distorted square-based pyramid. The N(μ−1,1) atom holds on the apical position of one CuII pyramid with an elongated bond length of 2.305 Å and on the basal plane of another distorted CuII pyramid with a bond length of 1.991 Å. The Cu–N(μ−1,1)–Cu angle is 117.4 (2)°. The copper(II) dimer forms a 1 D zig-zag chain via hydrogen bondings between azide ions, water molecules and the nitrate anion. Compound 2 consists of a double EO azido bridged NiII dimer with the Ni–N(μ−1,1)–Ni bond angle of 102.96 (13)°. The coordination geometry of NiII is octahedral. Their magnetic properties have been measured in the range from 300 to 2 K and correlated with the molecular structures. Compound 1 shows weak ferromagnetic interactions within the copper(II) dimer (J = 2.88 cm−1), despite the large EO azide bridge angle (117.4 (2)°). The intramolecular coupling between the NiII (S = 1) ions in compound 2 was found to be ferromagnetic (J = 27.87 cm−1).