EPR and HF-EPR study of a trinuclear MnII cluster encapsulated in one sandwich-type heteropolyanion

The Na12[Mn3(H2O)3(BiW9O33)2]·43H2O complex was investigated by EPR and HF-EPR spectroscopy. The three MnII ions are antiferromagnetically coupled, the coupling constant (J=−2.074 cm−1) being obtained from the temperature dependence of the linewidths of the HF-EPR signals in the 5–225 K temperature range. The S=7/2 spin state is populated at T=5 K and characterized by the isotropic g=2.0 factor, the axial D=−0.381 cm−1 and rhombic E=0.054 cm−1 zero field splitting parameters. X-band EPR spectra at room and liquid nitrogen temperatures (g1=2.013, g2=4.264) confirm the presence of MnII coupled ions.