The crystal structure described by Ca2Se4O11 crystallizes in the monoclinic Cc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), one O(8), and one O(9) atom to form distorted edge-sharing CaO7 pentagonal bipyramids. In the second Ca site, Ca(2) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), one O(7), and one O(9) atom to form distorted edge-sharing CaO7 pentagonal bipyramids. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(5), one O(7), and one O(9) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(10), one O(6), and one O(8) atom. In the third Se site, Se(3) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(11), and one O(3) atom. In the fourth Se site, Se(4) is bonded in a distorted trigonal non-coplanar geometry to one O(11), one O(2), and one O(4) atom. There are eleven inequivalent O sites. In the first O site, O(5) is bonded in a single-bond geometry to one Se(1) atom. In the second O site, O(6) is bonded in a single-bond geometry to one Se(2) atom. In the third O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Ca(2) and one Se(1) atom. In the fourth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Ca(1) and one Se(2) atom. In the fifth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Se(1) atom. In the sixth O site, O(10) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Se(2) atom. In the seventh O site, O(11) is bonded in a bent 120 degrees geometry to one Se(3) and one Se(4) atom. In the eighth O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Se(3) atom. In the ninth O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Se(4) atom. In the tenth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Se(3) atom. In the eleventh O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Se(4) atom. is represented by the CIF card [CIF]
data_Ca2Se4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.338
_cell_length_b   8.338
_cell_length_c   12.176
_cell_angle_alpha   65.119
_cell_angle_beta   65.119
_cell_angle_gamma   50.970
_symmetry_Int_Tables_number   1
_cell_volume   581.721
_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
  Ca  Ca0  1  0.229  0.728  0.928  1.0
  Ca  Ca1  1  0.262  0.778  0.573  1.0
  Ca  Ca2  1  0.778  0.262  0.073  1.0
  Ca  Ca3  1  0.728  0.229  0.428  1.0
  Se  Se4  1  0.623  0.943  0.326  1.0
  Se  Se5  1  0.063  0.372  0.176  1.0
  Se  Se6  1  0.372  0.063  0.676  1.0
  Se  Se7  1  0.943  0.623  0.826  1.0
  Se  Se8  1  0.361  0.838  0.093  1.0
  Se  Se9  1  0.180  0.662  0.384  1.0
  Se  Se10  1  0.662  0.180  0.884  1.0
  Se  Se11  1  0.838  0.361  0.593  1.0
  O  O12  1  0.508  0.645  0.013  1.0
  O  O13  1  0.346  0.493  0.482  1.0
  O  O14  1  0.493  0.346  0.982  1.0
  O  O15  1  0.645  0.508  0.513  1.0
  O  O16  1  0.114  0.925  0.094  1.0
  O  O17  1  0.059  0.893  0.421  1.0
  O  O18  1  0.893  0.059  0.921  1.0
  O  O19  1  0.925  0.114  0.594  1.0
  O  O20  1  0.637  0.928  0.189  1.0
  O  O21  1  0.072  0.366  0.313  1.0
  O  O22  1  0.366  0.072  0.813  1.0
  O  O23  1  0.928  0.637  0.689  1.0
  O  O24  1  0.391  0.991  0.426  1.0
  O  O25  1  0.013  0.604  0.076  1.0
  O  O26  1  0.604  0.013  0.576  1.0
  O  O27  1  0.991  0.391  0.926  1.0
  O  O28  1  0.642  0.152  0.293  1.0
  O  O29  1  0.860  0.346  0.207  1.0
  O  O30  1  0.346  0.860  0.707  1.0
  O  O31  1  0.152  0.642  0.793  1.0
  O  O32  1  0.394  0.666  0.249  1.0
  O  O33  1  0.666  0.394  0.749  1.0
[/CIF]
.
The crystal structure described by Ca2Se4O11 crystallizes in the monoclinic Cc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), one O(8), and one O(9) atom to form distorted edge-sharing CaO7 pentagonal bipyramids. In the second Ca site, Ca(2) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), one O(7), and one O(9) atom to form distorted edge-sharing CaO7 pentagonal bipyramids. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(5), one O(7), and one O(9) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one O(10), one O(6), and one O(8) atom. In the third Se site, Se(3) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(11), and one O(3) atom. In the fourth Se site, Se(4) is bonded in a distorted trigonal non-coplanar geometry to one O(11), one O(2), and one O(4) atom. There are eleven inequivalent O sites. In the first O site, O(5) is bonded in a single-bond geometry to one Se(1) atom. In the second O site, O(6) is bonded in a single-bond geometry to one Se(2) atom. In the third O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Ca(2) and one Se(1) atom. In the fourth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Ca(1) and one Se(2) atom. In the fifth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Se(1) atom. In the sixth O site, O(10) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Se(2) atom. In the seventh O site, O(11) is bonded in a bent 120 degrees geometry to one Se(3) and one Se(4) atom. In the eighth O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Se(3) atom. In the ninth O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Se(4) atom. In the tenth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Se(3) atom. In the eleventh O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Se(4) atom. is represented by the CIF card [CIF]
data_Ca2Se4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.338
_cell_length_b   8.338
_cell_length_c   12.176
_cell_angle_alpha   65.119
_cell_angle_beta   65.119
_cell_angle_gamma   50.970
_symmetry_Int_Tables_number   1
_cell_volume   581.721
_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
  Ca  Ca0  1  0.229  0.728  0.928  1.0
  Ca  Ca1  1  0.262  0.778  0.573  1.0
  Ca  Ca2  1  0.778  0.262  0.073  1.0
  Ca  Ca3  1  0.728  0.229  0.428  1.0
  Se  Se4  1  0.623  0.943  0.326  1.0
  Se  Se5  1  0.063  0.372  0.176  1.0
  Se  Se6  1  0.372  0.063  0.676  1.0
  Se  Se7  1  0.943  0.623  0.826  1.0
  Se  Se8  1  0.361  0.838  0.093  1.0
  Se  Se9  1  0.180  0.662  0.384  1.0
  Se  Se10  1  0.662  0.180  0.884  1.0
  Se  Se11  1  0.838  0.361  0.593  1.0
  O  O12  1  0.508  0.645  0.013  1.0
  O  O13  1  0.346  0.493  0.482  1.0
  O  O14  1  0.493  0.346  0.982  1.0
  O  O15  1  0.645  0.508  0.513  1.0
  O  O16  1  0.114  0.925  0.094  1.0
  O  O17  1  0.059  0.893  0.421  1.0
  O  O18  1  0.893  0.059  0.921  1.0
  O  O19  1  0.925  0.114  0.594  1.0
  O  O20  1  0.637  0.928  0.189  1.0
  O  O21  1  0.072  0.366  0.313  1.0
  O  O22  1  0.366  0.072  0.813  1.0
  O  O23  1  0.928  0.637  0.689  1.0
  O  O24  1  0.391  0.991  0.426  1.0
  O  O25  1  0.013  0.604  0.076  1.0
  O  O26  1  0.604  0.013  0.576  1.0
  O  O27  1  0.991  0.391  0.926  1.0
  O  O28  1  0.642  0.152  0.293  1.0
  O  O29  1  0.860  0.346  0.207  1.0
  O  O30  1  0.346  0.860  0.707  1.0
  O  O31  1  0.152  0.642  0.793  1.0
  O  O32  1  0.394  0.666  0.249  1.0
  O  O33  1  0.666  0.394  0.749  1.0
[/CIF]
.