It is found that the known regular structures of MnC₂O₄·2H₂O (I) do not allow to refine the powder X-ray pattern of (I) properly using the Rietveld method. Implementation of order-disorder scheme [28] via the including of appropriate displacement vector improves the refinement results. Also it is found that in the case of (I) the similar improvement may be achieved using the data on two phases of (I) obtained as result of decomposition MnC₂O₄·3H₂O single crystal in the mother solution after growth. Thermal decomposition of (I) produce the anhydrous γ-MnC₂O₄ (II) the structure of which is differ from the known α- and β-modifications of VIIIb transition metal oxalates. The solved ab initio from the powder pattern structure (II) (space group Pmna, a = 7.1333 (1), b = 5.8787 (1), c = 9.0186 (2) Å, V = 378.19 (1) ų, Z = 4 and D_x = 2.511 Mg m⁻³) contains seven-coordinated Mn atoms with Mn–O distances of 2.110–2.358 Å, and is not close-packed. Thermal decomposition of (II) in air flows via forming of amorphous MnO, the heating of which up to 723 K is accompanied by oxidation of MnO to Mn₂O₃ and further recrystallization of the latter.

发现，已知的MnC ₂ O ₄ ·2H ₂ O（I）的规则结构不能使用Rietveld方法适当地细化（I）的粉末X射线图案。通过包含适当的位移向量来实现有序-无序方案[28]可以改善优化结果。还发现在（I）的情况下，可以使用生长后在母液中分解MnC ₂ O ₄ ·3H ₂ O单晶而获得的（I）的两个相的数据来实现类似的改善。的（I）产生的无水热分解γ-MNC ₂ ö ₄（II）其结构不同于已知的VIIIb过渡金属草酸盐的α-和β-变体。该解决从头从粉末图案结构（II）（空间群PMNA中，a = 7.1333（1）中，b = 5.8787（1）中，c = 9.0186（2）埃，V = 378.19（1）埃³，Z = 4和D _x = 2.511 Mg m ^-3）包含7个配位的Mn原子，Mn-O距离为2.110-2.358Å，并且不是紧密堆积的。空气中（II）的热分解是通过形成无定形MnO来进行的，将其加热至723 K伴随着MnO氧化为Mn ₂ O ₃以及后者的进一步重结晶。