Observation of spin transition in an octahedrally coordinated manganese(II) compound

The thermal spin transition between a high-spin state (S = 5/2) and an intermediate-spin state (S = 3/2) of the octhahedrally coordinated Mn(II)(3d(5)) was observed in Rb(I)Mn(II)[Fe(III)(CN)(6)] with a very wide hysteresis loop over the temperature range of 231 to 304 K. This phenomenon is accompanied by a structural distortion from the face-centered cubic structure to the tetragonal one caused by a cooperative Jahn-Teller effect in the octahedral Fe(III)C-6 moiety. To our knowledge, the present spin transition is the first observation in compounds containing a six-coordinated Mn(II).