The compounds [1,40
-diium [CuCl4] (1) and [1,40
[CuBr4] (2) were prepared and their crystal structures and magnetic properties are reported.
The compounds are isomorphous and crystallize in the monoclinic space group C2/c. The cation
crystallizes in a two-fold disordered fashion with the terminal nitrogen and carbon atoms exhibiting
50% occupancies. This results in a crystal packing arrangement with significant hydrogen bonding that
is very similar to that observed in the corresponding 4,40
-bipyridinediium complexes. Temperature
dependent magnetic susceptibility measurements and room temperature EPR spectroscopy indicate
the presence of very weak antiferromagnetic exchange. The data were fit to the Curie–Weiss law and
yielded Weiss constants of −0.26(5) K (1) and −1.0(1) K (2).