Low-dimensional quantum magnetic systems: Synthesis, structure and magnetic behavior of (2,5-dimethylpyrazine)copper(II) chloride and synthesis and magnetic behavior of bis(2,6-dimethylpyrazine)copper(II) chloride

The synthesis, X-ray structure and magnetic susceptibility of (2,5-dimethylpyrazine)copper(II) chloride (1), and the synthesis and magnetic susceptibility of (2,6-dimethylpyrazine)2copper(II) chloride (2), are reported. Compound 1 crystallizes in the space group P21/c as a coordination polymer of Cu(II) ions bridged by 2,5-methylpyrazine. The resulting chains are magnetically linked via short chloride–chloride contacts. The magnetic susceptibility responds as a uniform Heisenberg chain (2J/k = −20(5) K) with a phase transition to three dimensional order near 5 K. Susceptibility data for compound 2 show that the compound is a linear chain coordination polymer with the copper ions linked by bihalide bridges. A fit to the model for a uniform Heisenberg chain yields 2J = −22.7(2) K.

Graphical abstract(2,5-Dimethylpyrazine)CuCl2 has been prepared and its structure and magnetic behavior determined. The compound crystallizes as chains of CuCl2 units linked by the pyrazine ligand. The chains pack such that each chain has four identical nearest neighbors. The magnetic data support a uniform chain model which crosses directly to three-dimensional behaviour.Figure optionsDownload full-size imageDownload as PowerPoint slide