Copper(II) Halide Salts with 1-(4′-Pyridyl)-Pyridinediium

Abstract

The compounds [1,4′-bipyridine]-1,1′-diium [CuCl4] (1) and [1,4′-bipyridine]-1,1′-diium [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 4,4′-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).

Revisiting the Role of Hydrogen Bonding in the Strong Dimer Superexchange of a 2D Copper(II) Halide Honeycomb-Like Lattice: Structural and Magnetic Study

“…The pyridine rings of the H 2 L 2+ ions are twisted relative to one another at an angle of 39.7°as observed previously. [23][24][25][26]43 Charge balance is attained via noncoordinated lattice chloride ions which stabilize the structure through hydrogen bonds to the pyridinium NH groups and both water and phenolic OH groups (Table 3), contributing significantly to the 3D structure of 1. Table 3 details some of the important hydrogen bonding interactions present in 1, specifically those which provide information regarding the superexchange discussion (vide infra).…”