Crystal structure and magnetic properties of K5.5Na1.5(PW10Cu2 H2O 2O38).13H2O. Substituted Keggin heteropolytungstates of the type PW10Cu2 containing exchange-coupled copper pairs

Crystals of a heteropolytungstate compound with the formula K5.5Na1.5(PW10Cu2 H2O 2O38).13H2O were subjected to X-ray diffraction, magneticsusceptibility and electronparamagnetic resonance spectroscopy examinations. Structural data identified the predominant alpha-Keggin coordination taken by the compound and the location of the copper ions. In addition, the exchange-coupled copper pairs, which were confirmed using magnetic measurements, formed two different exchange interactions and two anisotropies for the compounds.