Effect of Bridge Geometry on Exchange Coupling in Ligand-Bridged Copper(II) Dimers and Chains

Abstract

The singlet triplet splitting resulting from exchange coupling in three series of ligand-bridged copper(II) complexes is primarily controlled by the angle at the bridging ligand atom and by the length of the superexchange pathway. Magnetic and structural data exist for chloro-, bromo-, and sulfur-bridged complexes. The smooth correlation between the exchange coupling constant J and the quotient of structural parameters φr ₀ (where φ is the angle at the bridging ligand atom and r ₀, is the long out-of-plane bond distance) may be explained in terms of extended Hückel molecular-orbital theory, but the theory does not permit an explanation why only complexes which obey the simple correlation exist. It is predicted that a family of such structurally and magnetically related complexes should exist.