Crystal structures of three new copper(II) halide layered perovskites: structural, crystallographic, and magnetic correlations

Abstract

The compounds [1,40
\n-bipyridine]-1,10
\n-diium [CuCl4] (1) and [1,40
\n-bipyridine]-1,10
\n-diium
\n[CuBr4] (2) were prepared and their crystal structures and magnetic properties are reported.
\nThe compounds are isomorphous and crystallize in the monoclinic space group C2/c. The cation
\ncrystallizes in a two-fold disordered fashion with the terminal nitrogen and carbon atoms exhibiting
\n50% occupancies. This results in a crystal packing arrangement with significant hydrogen bonding that
\nis very similar to that observed in the corresponding 4,40
\n-bipyridinediium complexes. Temperature
\ndependent magnetic susceptibility measurements and room temperature EPR spectroscopy indicate
\nthe presence of very weak antiferromagnetic exchange. The data were fit to the Curie–Weiss law and
\nyielded Weiss constants of −0.26(5) K (1) and −1.0(1) K (2).