Toward prediction of magnetic properties in layered vanadyl phosphonates: correlation of magnetic exchange with the Hammett sigma parameter

The magnetic characteristics of the layered vanadyl phosphonates (LVPs) VO(O3PC6H4-X)*nH2O (X = p-NO2, m-F, p-Cl, p-F, H, p-CH3) were studied. The simple paramagnetism of the LVP featuring the strong electron withdrawing substituent X = p-NO2 gives way to increasing antiferromagnetic coupling between the V(super IV) centers as the electron-donating capability if X is increased. Findings revealed that magnetic coupling correlates with a simple measure of electronic perturbation of the exchange pathway in LVPs.