The Chain Manganates K₂₉Mn₁₇O₃₄, Rb₁₁Mn₈O₁₆ and Cs₄Mn₃O₆: a New Family of Mixed-valent One-dimensional Transition Metallates

Steffen Pfeiffer (1) , Jürgen Nuss (1)

1 Max-Planck-Institut für Festkörperforschung

Air and moisture sensitive K29Mn17O34, Rb11Mn8O16 and Cs4Mn3O6 have been prepared via the azide/nitrate route from stoichiometric mixtures of the precursors Mn2O3, AN3 and ANO3 (A = K, Rb, Cs) in special containers provided with silver inlays. Their compositions can be generalized as AxMnO2 with x varying between 1.703 and 1.333. According to the X-ray analysis of the crystal structures [K29Mn17O34: Ima2, Z = 4, a = 93.149(3), b = 10.0063(3), c = 6.0621(2) Å, 6585 independent reflections, R1 = 0.053, wR(all) = 0.143; Rb11Mn8O16: F222, Z = 16, a = 12.2096(4), b = 20.1595(7), c = 43.712(2) Å, 11534 independent reflections, R1 = 0.042, wR(all) = 0.131; Cs4Mn3O6: C222, Z = 8, a = 12.790(3), b = 21.123(4), c = 8.179(2) Å, 2212 independent reflections, R1 = 0.051, wR(all) = 0.122], the main feature of all three crystal structures are ¹_∞MnO₂^n– chains built up from partially distorted edge-sharing MnO4 tetrahedra. The alkali metal ions fill the space between the anionic entities forming honeycomb like arrangements. In all cases manganese is in a mixed-valent state but no full charge ordering is noticeable. The variations of the charges along the MnO₂^n– chains seem to be best described in terms of charge density waves. The magnetic susceptibilities show the dominance of strong antiferromagnetic interactions for the rubidium and the cesium compounds, whereas ferro- or ferrimagnetic interactions prevail in the potassium compound.

Mots clés: Physical Sciences

Steffen Pfeiffer, Jürgen Nuss. The Chain Manganates K₂₉Mn₁₇O₃₄, Rb₁₁Mn₈O₁₆ and Cs₄Mn₃O₆: a New Family of Mixed-valent One-dimensional Transition Metallates. Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 636 (1), pp.23. ⟨10.1002/zaac.200900269⟩. ⟨hal-00507772⟩