Hydrothermal synthesis, structure, spectroscopic and magnetic properties of a hexanuclear cluster: [{Mn(2,2′-bipy)2}2V4O12]

The hydrothermal reaction of Mn(OAC)2·4H2O, 2,2′-bipyridine (2,2′-bipy), NH4VO3, and H3BO3 in water at 180 °C for 48 h yields the bimetallic oxide [{Mn(2,2′-bipy)2V4O12] (1) with a {V4O12} ring linked through oxo groups of adjacent vanadium sites to two {Mn(2,2′-bipy)2} moieties. It crystallizes in the Orthorhombic system, space group Ibca, a=15.985(4) Å, b=16.860(4) Å, c=33.561(9) Å, Z=8, V=9045(4) Å3, R1=0.0447, wR2=0.0696. Variable temperature magnetic susceptibility measurements (4–300 K) show the occurrence of a weak antiferromagnetic interaction between the manganeses (II) (J=−0.295 cm−1). No splitting corresponding to the Mn hyperfine could have been observed in the ESR spectra.