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Synchrotron charge-density studies in materials chemistry: 16 K X-ray charge density of a new magnetic metal-organic framework material, [Mn2(C8H4O4)2(C3H7NO)2]

Acta Cryst. (2004). A60, 382–389 [doi:10.1107/S010876730401699X]

[MOF structure] The crystal structure of Mn2(C8H4O4)2(C3H7NO)2 at 16(1) K viewed along the a axis. The DMF molecules bonded directly to manganese occupy the voids.
Metal organic frameworks, MOFs, are of high current interest due to their gas storage abilities. This paper focuses on the physical properties of a magnetic Mn-based MOF, and it presents the 16(1) K structure and charge density, the heat capacity and the magnetic susceptibility of Mn2(C8H4O4)2(C3H7NO)2. Formal charge counting based on the crystal structure predicts two manganese atoms with +1.75 e charge and one with +2.50 e, while the topological analysis of the charge density results in Bader charges of +2, as predicted from synthesis. The effective magnetic moment is observed to be 5.96 μB, which is in excellent agreement with the experimentally determined charge density having close to one electron in each d orbital. 

R. D. Poulsen, A. Bentien, T. Graber and B. B. Iversen