Copper Acetate (II) acetate monohydrate, and similar Rh (II) and Cr (II) tetraacetates all adopt a "Chinese lantern" structure. One oxygen atom of each acetate is bonded to one copper atom, the Cu-O bond length is 197pm; two water molecule ligands occupy the upper and lower, and the Cu-O bond length is 220pm. The distance between two five-coordinated copper atoms is 265pm, which is close to the Cu-Cu distance (255pm) in metallic copper. This Cu2 (OAc) 4 (H2O) 2 dimer unit structure is mainly bonded by hydrogen bonding in the crystal. Other small molecular ligands such as dioxane, pyridine and aniline can replace the water in the dimer. molecule.
The two copper atoms interact with each other. At room temperature, the magnetic moment is 1.40BM, but it decreases with decreasing temperature (such as 0.36BM at 93K). At 253K, the magnetic susceptibility exhibits a maximum value, which is calculated from the adjacent The exchange between copper atoms is 286 cm-1, indicating that the copper atoms in the dimer are bonded by a weak covalent bond. Due to the opposite cancellation of the spin directions, Cu2 (OAc) 4 (H2O) 2 is essentially antimagnetic, and this structure has made an important contribution to the development of modern antiferromagnetic coupling theory.