The structure described by MgNbCu3S4 crystallizes in the trigonal R3m space group. Mg(1) is bonded in a 3-coordinate geometry to three equivalent Cu(1) and three equivalent S(1) atoms. Nb(1) is bonded to six equivalent Cu(1), one S(2), and three equivalent S(1) atoms to form distorted NbCu6S4 tetrahedra that share corners with three equivalent S(2)NbCu3 tetrahedra, corners with six equivalent Nb(1)Cu6S4 tetrahedra, and  a faceface with one S(2)NbCu3 tetrahedra. Cu(1) is bonded in a 7-coordinate geometry to one Mg(1), two equivalent Nb(1), one S(2), and three equivalent S(1) atoms. There are two inequivalent S sites. In the first S site, S(1) is bonded in a distorted pentagonal planar geometry to one Mg(1), one Nb(1), and three equivalent Cu(1) atoms. In the second S site, S(2) is bonded to one Nb(1) and three equivalent Cu(1) atoms to form SNbCu3 tetrahedra that share corners with three equivalent Nb(1)Cu6S4 tetrahedra and  a faceface with one Nb(1)Cu6S4 tetrahedra. is represented by the CIF card [CIF]
data_MgNbCu3S4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.685
_cell_length_b   5.685
_cell_length_c   5.685
_cell_angle_alpha   88.837
_cell_angle_beta   91.163
_cell_angle_gamma   91.163
_symmetry_Int_Tables_number   1
_cell_volume   183.659
_cell_formula_units_Z   1
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
  Mg  Mg0  1  0.686  0.314  0.314  1.0
  Nb  Nb1  1  0.985  0.015  0.015  1.0
  Cu  Cu2  1  0.000  1.000  0.518  1.0
  Cu  Cu3  1  0.000  0.518  1.000  1.0
  Cu  Cu4  1  0.482  1.000  1.000  1.0
  S  S5  1  0.761  0.740  0.239  1.0
  S  S6  1  0.761  0.239  0.740  1.0
  S  S7  1  0.231  0.769  0.769  1.0
  S  S8  1  0.260  0.239  0.239  1.0
[/CIF]
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The structure described by MgNbCu3S4 crystallizes in the trigonal R3m space group. Mg(1) is bonded in a 3-coordinate geometry to three equivalent Cu(1) and three equivalent S(1) atoms. Nb(1) is bonded to six equivalent Cu(1), one S(2), and three equivalent S(1) atoms to form distorted NbCu6S4 tetrahedra that share corners with three equivalent S(2)NbCu3 tetrahedra, corners with six equivalent Nb(1)Cu6S4 tetrahedra, and  a faceface with one S(2)NbCu3 tetrahedra. Cu(1) is bonded in a 7-coordinate geometry to one Mg(1), two equivalent Nb(1), one S(2), and three equivalent S(1) atoms. There are two inequivalent S sites. In the first S site, S(1) is bonded in a distorted pentagonal planar geometry to one Mg(1), one Nb(1), and three equivalent Cu(1) atoms. In the second S site, S(2) is bonded to one Nb(1) and three equivalent Cu(1) atoms to form SNbCu3 tetrahedra that share corners with three equivalent Nb(1)Cu6S4 tetrahedra and  a faceface with one Nb(1)Cu6S4 tetrahedra. is represented by the CIF card [CIF]
data_MgNbCu3S4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.685
_cell_length_b   5.685
_cell_length_c   5.685
_cell_angle_alpha   88.837
_cell_angle_beta   91.163
_cell_angle_gamma   91.163
_symmetry_Int_Tables_number   1
_cell_volume   183.659
_cell_formula_units_Z   1
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
  Mg  Mg0  1  0.686  0.314  0.314  1.0
  Nb  Nb1  1  0.985  0.015  0.015  1.0
  Cu  Cu2  1  0.000  1.000  0.518  1.0
  Cu  Cu3  1  0.000  0.518  1.000  1.0
  Cu  Cu4  1  0.482  1.000  1.000  1.0
  S  S5  1  0.761  0.740  0.239  1.0
  S  S6  1  0.761  0.239  0.740  1.0
  S  S7  1  0.231  0.769  0.769  1.0
  S  S8  1  0.260  0.239  0.239  1.0
[/CIF]
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