The material described by MgS2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with two equivalent S(2)O4 tetrahedra and corners with four equivalent S(1)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form MgO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra and corners with four equivalent S(2)O4 tetrahedra. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and  a cornercorner with one S(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-47°. In the second S site, S(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, and  a cornercorner with one S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-44°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(2) and one S(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one S(1) and one S(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mg(2) and one S(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Mg(2) and one S(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one S(2) atom. is represented by the CIF file [CIF]
data_MgS2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.902
_cell_length_b   6.944
_cell_length_c   8.214
_cell_angle_alpha   92.421
_cell_angle_beta   94.783
_cell_angle_gamma   106.171
_symmetry_Int_Tables_number   1
_cell_volume   266.981
_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
  Mg  Mg0  1  0.000  0.500  0.000  1.0
  Mg  Mg1  1  0.500  0.000  0.500  1.0
  S  S2  1  0.506  0.646  0.768  1.0
  S  S3  1  0.494  0.354  0.232  1.0
  S  S4  1  0.131  0.250  0.688  1.0
  S  S5  1  0.869  0.750  0.312  1.0
  O  O6  1  0.733  0.560  0.816  1.0
  O  O7  1  0.267  0.440  0.184  1.0
  O  O8  1  0.343  0.681  0.898  1.0
  O  O9  1  0.657  0.319  0.102  1.0
  O  O10  1  0.591  0.811  0.667  1.0
  O  O11  1  0.409  0.189  0.333  1.0
  O  O12  1  0.285  0.478  0.638  1.0
  O  O13  1  0.715  0.522  0.362  1.0
  O  O14  1  0.897  0.191  0.562  1.0
  O  O15  1  0.103  0.809  0.438  1.0
  O  O16  1  0.340  0.142  0.679  1.0
  O  O17  1  0.660  0.858  0.321  1.0
  O  O18  1  0.053  0.271  0.852  1.0
  O  O19  1  0.947  0.729  0.148  1.0
[/CIF]
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The material described by MgS2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with two equivalent S(2)O4 tetrahedra and corners with four equivalent S(1)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form MgO6 octahedra that share corners with two equivalent S(1)O4 tetrahedra and corners with four equivalent S(2)O4 tetrahedra. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and  a cornercorner with one S(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-47°. In the second S site, S(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, and  a cornercorner with one S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-44°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(2) and one S(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one S(1) and one S(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mg(2) and one S(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Mg(2) and one S(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one S(2) atom. is represented by the CIF file [CIF]
data_MgS2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.902
_cell_length_b   6.944
_cell_length_c   8.214
_cell_angle_alpha   92.421
_cell_angle_beta   94.783
_cell_angle_gamma   106.171
_symmetry_Int_Tables_number   1
_cell_volume   266.981
_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
  Mg  Mg0  1  0.000  0.500  0.000  1.0
  Mg  Mg1  1  0.500  0.000  0.500  1.0
  S  S2  1  0.506  0.646  0.768  1.0
  S  S3  1  0.494  0.354  0.232  1.0
  S  S4  1  0.131  0.250  0.688  1.0
  S  S5  1  0.869  0.750  0.312  1.0
  O  O6  1  0.733  0.560  0.816  1.0
  O  O7  1  0.267  0.440  0.184  1.0
  O  O8  1  0.343  0.681  0.898  1.0
  O  O9  1  0.657  0.319  0.102  1.0
  O  O10  1  0.591  0.811  0.667  1.0
  O  O11  1  0.409  0.189  0.333  1.0
  O  O12  1  0.285  0.478  0.638  1.0
  O  O13  1  0.715  0.522  0.362  1.0
  O  O14  1  0.897  0.191  0.562  1.0
  O  O15  1  0.103  0.809  0.438  1.0
  O  O16  1  0.340  0.142  0.679  1.0
  O  O17  1  0.660  0.858  0.321  1.0
  O  O18  1  0.053  0.271  0.852  1.0
  O  O19  1  0.947  0.729  0.148  1.0
[/CIF]
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