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FeXMn1-XS (0 <x< 0.3) synthesized on the basis of {\alpha}-MnS are the novel Mott-type substances with the rock salt structure. Neutron diffraction study shows that the shift of the Neel temperature of these materials from 150 (x = 0) to 200 K (x = 0.29) under the action of chemical pressure (x) is accompanied by a decrease in the cubic NaCl lattice parameters. The structural transition with a change in crystal symmetry and a decrease in resistance before the magnetic transition at x = 0.25 is found. Therefore, FeXMn1-XS are interesting materials for both fundamental study of the interrelation between the magnetic, electrical, and structural properties in systems with the strong electron correlations of a MnO-type and application.