Three Novel Metal Supramolecular Polymers Directed by 1,2-bis(pyridinium)ethane Cation: Syntheses and Crystal Structures

Abstract

Three novel supramolecular polymers, [(Cd₂Cl₃)(H₂O)₂(N₃)₃ (bpe)] (bpe = 1,2-bis(pyridinium)ethane)(1), [(ZnCl₄)(bpe) (ZnCl₃N₃)(bpe)](2), and [(CdCl₂Br₂)(bpe)] (3), were synthesized in polar organic solvents using solvent diffusion method, and the three compounds have been characterized by single-crystal X-ray diffraction and IR spectroscopy. Compound 1 comprises discrete bpe cations and centrosymmetric tetrameric anions in which cadmium(II) centers have two distinct coordination modes (four- and six-coordinated) bridged by end-on azide. The three-dimensional (3-D) organic–inorganic hybrid supramolecular structure is formed by a series of hydrogen bonds (O-H···Cl and O-H···N). Compared with compound 1, the reactants of complex 2 also include sodium azide, bpe²⁺ and transition metal salt except that ZnCl₂ instead of CdCl₂, but compound 2 is only a mononuclear complex with two different tetrahedral configuration of Zn centers. The mononuclear compound 3 crystallizes in orthorhombic system with the space group Pnma, and the Cd(I) atom is four-coordinated in a distorted tetrahedral geometry by two terminal Cl and two terminal Br.

Keywords:

• azide
• crystal structure
• tetranuclear cadmium polymer