Synthesis, crystal structure, and magnetism of a 1-D Cu^II chain complex with a mono-bromide bridge

Abstract

A 1-D Cu^II chain, [Cu(μ-Br)(phenmp)₂]_n·(ClO₄)_n (phenmp = 2-(4-methyl-pyrazol-1H-yl)-1,10-phenanthroline), was synthesized and its crystal structure was determined by X-ray crystallography. Cu^II is located in a distorted square-pyramidal geometry, with the mono-bromide – a bridge linking two adjacent Cu^II ions with a separation of 3.788 Å. The result is a uniform 1-D chain that lies along the c axis. Mono-halide-bridged models have not been reported very often. The fitting for the data of the variable-temperature (2.00–330 K) magnetic susceptibilities gave a ferromagnetic interaction of J = 5.11 cm⁻¹ (H = −2JS ₁ S ₂) for adjacent-bridged Cu^II ions. Comparing mono-halide bridged Cu^II complexes, trigonal-bipyramidal geometry has strong magnetic interactions, whereas square-pyramidal geometry has weak magnetic interactions. In mono-bromide bridged Cu^II complexes, the Cu–Br–Cu angle is related to the magnetic coupling signs with small Cu–Br–Cu angle favoring ferromagnetic interaction, while large Cu–Br–Cu angle results in antiferromagnetic interactions.

Keywords:

• Magnetism
• Copper(II) complex
• Crystal structure
• Bromide

Acknowledgments

This work was financially supported by the Natural Science Foundation of China (No. 20971080), the Natural Science Foundation of Shandong Province (Grant No. ZR2010BL016) and the Project of Shandong Province Higher Educational Science and Technology Program (Grant No. J13LD53).