Exchange coupling in mu-aqua:mu-oxo vs. di-mu-hydroxo dinuclear Cu(II) compounds: a density functional study

Theoretical methods based on density functional theory have been applied to study the differences in exchange coupling between the di-mu-hydroxo and mu-aqua:mu-oxo tautomers of a dinuclear Cu(II) complex. The calculations indicate that the two compounds are totally different from a magnetic point of view. The transfer of one proton from one of the two hydroxo bridges to the other leaves an asymmetric structure with only one effective exchange pathway through the oxo bridge. The coordinated water molecule and an associated perchlorate counterion, although not directly involved in the exchange coupling, play an important role in the magnetic properties of this compound since their presence is crucial in the determination of the geometrical details of the Cu-O(ox)-Cu linkage and hence in the exchange coupling between the copper atoms.