A mixed-valence copper chloride coordination polymer composed of one-dimensional cationic and anionic substructures

Abstract

A new three-dimensional (3D) coordination polymer [{(CuCl2)-Cl-II(Hdatrz)(2)}((Cu2Cl4)-Cl-I)](n) (1) that consists of two independent cationic and anionic substructures has been synthesized from the reaction of 3,5-diamino-1,2,4-triazole (datrz) with (CuCl)-Cl-I and (CuCl2)-Cl-II. The cationic subunit, [(CuCl2)-Cl-II(Hdatrz)(2)](2+), has a one-dimensional (1D) structure based on [(CuCl2)-Cl-II(Hdatrz)(2)Cl-2] octahedral units, while the anionic component [(Cu2Cl4)-Cl-I](2-) consists of 1D chains of edge-sharing CuCl4 tetrahedra. The cationic and anionic chains are linked through interionic hydrogen bonding. The protonated datrz ligand plays an essential role in constructing the supramolecular framework. The magnetic Cu-II (d(9)) ion occupies the octahedral center of the cationic substructure, while the non-magnetic Cu-I (d(10)) ion resides in the tetrahedral core of the anionic substructure. The temperature-dependent magnetic susceptibility of 1 reveals a typical paramagnetic behavior, and the Curie-Weiss fit shows a magnetic moment of 2.04 mu(B) per Cu-II. There is weak antiferromagnetic ordering below a Neel temperature of 2.46 K, presumably due to an antiferromagnetic interaction between neighboring Cu-II ions linked by two Cl ligands. The EPR spectra of 1 suggest that the [(CuCl2)-Cl-II(Hdatrz)(2)Cl-2] subunit has a tetragonally elongated octahedral geometry and the complex 1 contains mixed-valence Cu-I and Cu-II species. In addition, we discovered a novel molecular compound with a stoichiometry of (H(2)datrz)Cl-2 (2), which was prepared by the reaction of concentrated hydrochloric acid with datrz in the absence of copper chlorides. X-ray crystal structure determination shows that the compound consists of an unusual di-protonated H(2)datrz(2+) cation and two charge-compensating Cl- anions.