Structural Transition Induced by Charge-Transfer in RbMn[Fe(CN)6] –Investigation by Synchrotron-Radiation X-ray Powder Analysis–

Temperature dependence of atomic coordinates is determined for RbMn[Fe(CN) 6 ] by means of synchrotron-radiation (SR) X-ray powder structural analysis. We observed a structural transition from the cubic (F\(4̄\)3m; Z = 4) to the tetragonal (I\(4̄\)m2; Z = 2) phase at ≈ 210 K in the cooling run and at ≈ 300 K in the warming run. In the low-temperature tetragonal phase, we found Jahn–Tellar type distortion of the MnN 6 octahedra and compression of the averaged Fe–C bond distance. These structural data suggest that the structural transition is triggered by the inter-metallic charge-transfer from the Mn(II) site to the Fe(III) site.