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

Abstract

An asymmetric single EO azido bridged dinuclear copper(II) complex, [Cu 2(dmterpy) 2(μ-1,1-N 3)(N 3) 2] · NO 3 · (H 2O) 2 1 [dmterpy = 5,5″-dimethyl-2,2′:6′,2″-terpyridine], and a double EO azido bridged dinuclear nickel(II) complex, [Ni 2(pbdiim) 4(μ-1,1-N 3) 2] · 2(N 3) · 6(H 2O) 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 Cu II dimer in which each Cu II 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 Cu II pyramid with an elongated bond length of 2.305 Å and on the basal plane of another distorted Cu II 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 Ni II dimer with the Ni–N (μ−1,1)–Ni bond angle of 102.96 (13)°. The coordination geometry of Ni II 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 Ni II ( S = 1) ions in compound 2 was found to be ferromagnetic ( J = 27.87 cm −1).