Аннотация:A method has been developed for synthesis of Mn8Cl3O10 oxochloride in an Ar flow (600°C, 8 h) from MnCl2 and MnO2. Some of the Mn2+ cations in this compound have been replaced by Mg2+ cations to fit the Mg0.6Mn7.4Cl3O10 formula. The composition of the oxochloride has been determined from the results of Rietveld refinement of its crystal structure using X-ray powder diffraction data and confirmed by X-ray electron probe analysis. It has been found that the Mg2+ cations in the structure preferentially occupy positions in a cubic array of oxygen atoms (MO8) rather than octahedral MCl6 sites.