The material structure described by Ca2S2O9 crystallizes in the trigonal P3_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. There are two inequivalent S sites. In the first S site, S(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second S site, S(2) is bonded in a tetrahedral geometry to one O(5), one O(6), one O(7), and one O(8) atom. There are nine inequivalent O sites. In the first O site, O(8) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. In the second O site, O(9) is bonded in a single-bond geometry to one Ca(2) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the seventh O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. In the eighth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. In the ninth O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. is represented by the CIF file [CIF]
data_Ca2S2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.069
_cell_length_b   7.069
_cell_length_c   12.773
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   552.715
_cell_formula_units_Z   3
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
  Ca  Ca0  1  0.811  0.138  0.329  1.0
  Ca  Ca1  1  0.862  0.673  0.663  1.0
  Ca  Ca2  1  0.327  0.189  0.996  1.0
  Ca  Ca3  1  0.331  0.196  0.497  1.0
  Ca  Ca4  1  0.804  0.135  0.830  1.0
  Ca  Ca5  1  0.865  0.669  0.164  1.0
  S  S6  1  0.789  0.123  0.083  1.0
  S  S7  1  0.877  0.666  0.416  1.0
  S  S8  1  0.334  0.211  0.749  1.0
  S  S9  1  0.341  0.211  0.248  1.0
  S  S10  1  0.789  0.130  0.582  1.0
  S  S11  1  0.870  0.659  0.915  1.0
  O  O12  1  0.593  0.070  0.018  1.0
  O  O13  1  0.930  0.523  0.352  1.0
  O  O14  1  0.477  0.407  0.685  1.0
  O  O15  1  0.848  0.314  0.152  1.0
  O  O16  1  0.686  0.534  0.486  1.0
  O  O17  1  0.466  0.152  0.819  1.0
  O  O18  1  0.749  0.939  0.153  1.0
  O  O19  1  0.061  0.810  0.487  1.0
  O  O20  1  0.190  0.251  0.820  1.0
  O  O21  1  0.970  0.173  0.007  1.0
  O  O22  1  0.827  0.797  0.341  1.0
  O  O23  1  0.203  0.030  0.674  1.0
  O  O24  1  0.199  0.255  0.319  1.0
  O  O25  1  0.745  0.944  0.652  1.0
  O  O26  1  0.056  0.801  0.985  1.0
  O  O27  1  0.483  0.404  0.183  1.0
  O  O28  1  0.596  0.079  0.516  1.0
  O  O29  1  0.921  0.517  0.850  1.0
  O  O30  1  0.469  0.145  0.317  1.0
  O  O31  1  0.855  0.323  0.651  1.0
  O  O32  1  0.677  0.531  0.984  1.0
  O  O33  1  0.205  0.031  0.173  1.0
  O  O34  1  0.969  0.174  0.506  1.0
  O  O35  1  0.826  0.795  0.839  1.0
  O  O36  1  0.221  0.694  0.192  1.0
  O  O37  1  0.306  0.527  0.525  1.0
  O  O38  1  0.473  0.779  0.858  1.0
[/CIF]
.
The material structure described by Ca2S2O9 crystallizes in the trigonal P3_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. There are two inequivalent S sites. In the first S site, S(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second S site, S(2) is bonded in a tetrahedral geometry to one O(5), one O(6), one O(7), and one O(8) atom. There are nine inequivalent O sites. In the first O site, O(8) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. In the second O site, O(9) is bonded in a single-bond geometry to one Ca(2) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(1) atom. In the seventh O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. In the eighth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. In the ninth O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one S(2) atom. is represented by the CIF file [CIF]
data_Ca2S2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.069
_cell_length_b   7.069
_cell_length_c   12.773
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   552.715
_cell_formula_units_Z   3
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
  Ca  Ca0  1  0.811  0.138  0.329  1.0
  Ca  Ca1  1  0.862  0.673  0.663  1.0
  Ca  Ca2  1  0.327  0.189  0.996  1.0
  Ca  Ca3  1  0.331  0.196  0.497  1.0
  Ca  Ca4  1  0.804  0.135  0.830  1.0
  Ca  Ca5  1  0.865  0.669  0.164  1.0
  S  S6  1  0.789  0.123  0.083  1.0
  S  S7  1  0.877  0.666  0.416  1.0
  S  S8  1  0.334  0.211  0.749  1.0
  S  S9  1  0.341  0.211  0.248  1.0
  S  S10  1  0.789  0.130  0.582  1.0
  S  S11  1  0.870  0.659  0.915  1.0
  O  O12  1  0.593  0.070  0.018  1.0
  O  O13  1  0.930  0.523  0.352  1.0
  O  O14  1  0.477  0.407  0.685  1.0
  O  O15  1  0.848  0.314  0.152  1.0
  O  O16  1  0.686  0.534  0.486  1.0
  O  O17  1  0.466  0.152  0.819  1.0
  O  O18  1  0.749  0.939  0.153  1.0
  O  O19  1  0.061  0.810  0.487  1.0
  O  O20  1  0.190  0.251  0.820  1.0
  O  O21  1  0.970  0.173  0.007  1.0
  O  O22  1  0.827  0.797  0.341  1.0
  O  O23  1  0.203  0.030  0.674  1.0
  O  O24  1  0.199  0.255  0.319  1.0
  O  O25  1  0.745  0.944  0.652  1.0
  O  O26  1  0.056  0.801  0.985  1.0
  O  O27  1  0.483  0.404  0.183  1.0
  O  O28  1  0.596  0.079  0.516  1.0
  O  O29  1  0.921  0.517  0.850  1.0
  O  O30  1  0.469  0.145  0.317  1.0
  O  O31  1  0.855  0.323  0.651  1.0
  O  O32  1  0.677  0.531  0.984  1.0
  O  O33  1  0.205  0.031  0.173  1.0
  O  O34  1  0.969  0.174  0.506  1.0
  O  O35  1  0.826  0.795  0.839  1.0
  O  O36  1  0.221  0.694  0.192  1.0
  O  O37  1  0.306  0.527  0.525  1.0
  O  O38  1  0.473  0.779  0.858  1.0
[/CIF]
.