Syntheses, crystal structures and characterizations of three new copper(II) azide coordination polymers with 1,2,4-triazole ligands

Three new copper(II) azide coordination polymers with derivatives of 1,2,4-triazole as bridging coligands, namely [Cu2(admtrz)2(N3)4]n (1) (admtrz = 4-amino-3,5-dimethyl-1,2,4-triazole), [Cu(4-abpt)(N3)2]n·2nH2O (2) (4-abpt = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole) and [Cu3(2-ptrz)2(N3)6]n (3) (2-ptrz = 4-(2-pyridyl)-1,2,4-triazole), were prepared and characterized by elemental analyses, IR spectra and X-ray structural analyses. Compound 1 has a 1D chain structure in which Cu(II) ions are bridged by end-on (EO) azides and admtrz ligands. This compound contains three kinds of coordination modes for Cu(II) ions, including tetrahedral, square pyramidal and octahedral geometries. Compound 2 displays an interesting 3D framework structure, in which the azide ligands link Cu(II) ions in end-to-end (EE) mode affording a 2D square layer. This 2D layers are further bridged by bent 4-abpt ligands to form an interesting 3D framework. Furthermore, this structure also exhibits an alpha-Po net topology. Compound 3 displays a 1D rectangle-like chain structure linked by azides adopting end-on (EO) and end-to-end (EE) modes and 2-ptrz ligands. The IR and thermal stabilities of these coordination polymers 1–3 have also been studied.