Acta Crystallographica Section B

Structural Science

Volume 55, Part 2 (April 1999)

research papers

Acta Cryst. (1999). B55, 186-191 [ doi:10.1107/S0108768198011586 ]

Crystallographic disorder in mixed-valent dioxo-bridged Mn^III,IV complexes. [Mn₂O₂(bpy)₄][Ce(NO₃)₆].5H₂O

D. Ramalakshmi and M. V. Rajasekharan

Abstract: The structure of tetrakis(2,2'-bipyridine)di- [mu] -oxo-dimanganese(3+) hexanitratocerate(3-) pentahydrate, [Mn₂O₂(bpy)₄][Ce(NO₃)₆].5H₂O, is described; M_r = 1368.88, monoclinic, C2/c, a = 12.940 (3), b = 18.060 (2), c = 22.54 (1) Å, = 96.29 (2)°, V = 5237 (3) Å³, T = 132 K, Z = 4, F(000) = 2752, D_x = 1.736 Mg m^-3, (Mo K [alpha] ) = 0.71073 Å, = 1.429 mm^-1, R(F²) = 0.0358, wR(F²) = 0.0783 for 4877 reflections with I > 2(I). The cation does not have crystallographically distinguishable Mn atoms. An analysis of the atomic displacement ellipsoids and Mn-N bond distortions has been used to develop a model for the disorder in this type of mixed-valent complex. The anion, Ce(NO₃) $_6^{3-}$ , has a distorted icosahedral geometry.