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, [Cu3(atrz)2(N3)6] 1 and [Cu(atrz)2(N3)]NO32 (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)°], and larger Cu–N–Cu [118.7(2)°]. 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)°] and Cu–N–Cu 104.05(12)°. The nearest-neighbour Cu· · ·Cu distances are 3.4496(7) Å for 1 and 3.5034(6) Å 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.