Abstract
The magnetic susceptibility of (NH4)6MnMo9O32.8H2O has been measured from 1·7 K to 260 K at field strengths up to 50 kG, while the magnetic anisotropy has been measured from 4·58 K to 260 K. After correcting for Mn(II) impurities the results are in reasonable agreement with published electronic paramagnetic resonance (E.P.R.) data and indicate that the zero field splitting (Z.F.S.) parameter D is positive and probably independent of temperature. Crystal-field calculations on the complete d 3 configuration suggest low values of the spin orbit coupling constant ζ and/or the orbital reduction parameter k.