Linear trinuclear and one-dimensional copper(II) complexes containing co-bridging end-on azido and triazole ligands.: Crystal structures and magnetic properties of [Cu3(atrz)2(N3)6] and [Cu(atrz)2(N3)]NO3 (atrz=4-amino-1,2,4-triazole)

New complexes with 1,2,4-triazole and end-on azido bridging ligands, [Cu-3(atrz)(2)(N-3)(6)] 1 and [Cu(atrz)(2)(N-3)]NO3 2 (atrz = 4-amino-1,2,4-triazole), have been prepared and structurally determined. Complex 1 has a linear trinuclear copper(II) structure with bridging bond angles Cu-N-N (atrz) [119.3(3) and 123.4(3)degrees], and larger Cu-N-Cu [118.7(2)degrees]. In 2 the copper(II) ions are linked by one end-on azido and two triazole bridges forming a cationic chain with Cu-N-N (equatorial atrz) [121.0(2) and 122.3(2)degrees] and Cu-N-Cu 104.05(12)degrees. The nearest-neighbour Cu ... Cu distances are 3.4496(7) Angstrom for 1 and 3.5034(6) Angstrom for 2. The copper(II) ions are strongly antiferromagnetically coupled with J = -108.8 cm(-1) for 1, and weakly with J = -17.7 cm(-1) for 2. The nature and the magnitude of the antiferromagnetic exchange of both complexes are discussed based on their structures.