Formation of Antiferromagnetic Spin Dimer Induced by Orientation Ordering of Water Molecule in Fluorinated Pincered Cu(II) Complexes

Abstract Pincered transition metal complexes show rich crystal structures owing to intra- and intermolecular hydrogen bonding. Their structural diversity also motivates us to investigate their magnetic interactions mediated by hydrogen bonding. In this study, we report the structural and magnetic properties of copper mononuclear complexes 2FH-CuCl2·H2O and 3F-CuCl2·H2O, with a fluorinated pincered ligand. Both compounds are composed of a uniform chain of molecules coupled by O–H···Cl classical and improper hydrogen-bonding interactions. These compounds exhibit a structural transition induced by orientation ordering of water molecules, which drives bond alternation. The bond alternation also induces dimerization in magnetic interactions between nearest-neighbor Cu ions, evidenced by the magnetization following the isolated antiferromagnetic spin dimer model.