The material structure described by MgTmS3 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form MgS6 octahedra that share corners with eight equivalent Tm(1)S4 tetrahedra and edges with three equivalent Mg(1)S6 octahedra. Tm(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form distorted TmS4 tetrahedra that share corners with eight equivalent Mg(1)S6 octahedra and  an edgeedge with one Tm(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-74°. There are two inequivalent S sites. In the first S site, S(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Tm(1) atom. In the second S site, S(2) is bonded to two equivalent Mg(1) and two equivalent Tm(1) atoms to form edge-sharing STm2Mg2 tetrahedra. is represented by the CIF file [CIF]
data_TmMgS3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.965
_cell_length_b   6.965
_cell_length_c   6.622
_cell_angle_alpha   76.524
_cell_angle_beta   76.524
_cell_angle_gamma   118.693
_symmetry_Int_Tables_number   1
_cell_volume   250.646
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Tm  Tm0  1  0.200  0.200  0.686  1.0
  Tm  Tm1  1  0.800  0.800  0.314  1.0
  Mg  Mg2  1  0.337  0.663  0.000  1.0
  Mg  Mg3  1  0.663  0.337  0.000  1.0
  S  S4  1  0.111  0.779  0.804  1.0
  S  S5  1  0.889  0.221  0.196  1.0
  S  S6  1  0.221  0.889  0.196  1.0
  S  S7  1  0.779  0.111  0.804  1.0
  S  S8  1  0.462  0.462  0.260  1.0
  S  S9  1  0.538  0.538  0.740  1.0
[/CIF]
.
The material structure described by MgTmS3 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form MgS6 octahedra that share corners with eight equivalent Tm(1)S4 tetrahedra and edges with three equivalent Mg(1)S6 octahedra. Tm(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form distorted TmS4 tetrahedra that share corners with eight equivalent Mg(1)S6 octahedra and  an edgeedge with one Tm(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-74°. There are two inequivalent S sites. In the first S site, S(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Tm(1) atom. In the second S site, S(2) is bonded to two equivalent Mg(1) and two equivalent Tm(1) atoms to form edge-sharing STm2Mg2 tetrahedra. is represented by the CIF file [CIF]
data_TmMgS3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.965
_cell_length_b   6.965
_cell_length_c   6.622
_cell_angle_alpha   76.524
_cell_angle_beta   76.524
_cell_angle_gamma   118.693
_symmetry_Int_Tables_number   1
_cell_volume   250.646
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Tm  Tm0  1  0.200  0.200  0.686  1.0
  Tm  Tm1  1  0.800  0.800  0.314  1.0
  Mg  Mg2  1  0.337  0.663  0.000  1.0
  Mg  Mg3  1  0.663  0.337  0.000  1.0
  S  S4  1  0.111  0.779  0.804  1.0
  S  S5  1  0.889  0.221  0.196  1.0
  S  S6  1  0.221  0.889  0.196  1.0
  S  S7  1  0.779  0.111  0.804  1.0
  S  S8  1  0.462  0.462  0.260  1.0
  S  S9  1  0.538  0.538  0.740  1.0
[/CIF]
.