The structure described by K2Ca2(CO3)3 crystallizes in the trigonal R3 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(4) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form distorted edge-sharing CaO7 pentagonal bipyramids. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(4), and three equivalent O(5) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(4), one O(5), and one O(6) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(2), one Ca(1), one Ca(2), and one C(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), two equivalent Ca(1), and one C(2) atom. In the third O site, O(3) is bonded to two equivalent K(2), one Ca(1), and one C(2) atom to form distorted corner-sharing OK2CaC tetrahedra. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), one Ca(2), and one C(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ca(1), one Ca(2), and one C(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one K(2), two equivalent Ca(1), and one C(1) atom. is represented by the CIF card [CIF]
data_K2Ca2(CO3)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.042
_cell_length_b   8.042
_cell_length_c   8.042
_cell_angle_alpha   107.981
_cell_angle_beta   107.981
_cell_angle_gamma   107.981
_symmetry_Int_Tables_number   1
_cell_volume   421.022
_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
  K  K0  1  0.129  0.129  0.129  1.0
  K  K1  1  0.902  0.444  0.300  1.0
  K  K2  1  0.300  0.902  0.444  1.0
  K  K3  1  0.444  0.300  0.902  1.0
  Ca  Ca4  1  0.975  0.493  0.829  1.0
  Ca  Ca5  1  0.493  0.829  0.975  1.0
  Ca  Ca6  1  0.829  0.975  0.493  1.0
  Ca  Ca7  1  0.553  0.553  0.553  1.0
  C  C8  1  0.583  0.197  0.386  1.0
  C  C9  1  0.067  0.821  0.734  1.0
  C  C10  1  0.734  0.067  0.821  1.0
  C  C11  1  0.821  0.734  0.067  1.0
  C  C12  1  0.197  0.386  0.583  1.0
  C  C13  1  0.386  0.583  0.197  1.0
  O  O14  1  0.639  0.897  0.670  1.0
  O  O15  1  0.899  0.188  0.845  1.0
  O  O16  1  0.665  0.111  0.944  1.0
  O  O17  1  0.526  0.281  0.283  1.0
  O  O18  1  0.649  0.282  0.573  1.0
  O  O19  1  0.571  0.024  0.303  1.0
  O  O20  1  0.283  0.526  0.281  1.0
  O  O21  1  0.111  0.944  0.665  1.0
  O  O22  1  0.303  0.571  0.024  1.0
  O  O23  1  0.573  0.649  0.282  1.0
  O  O24  1  0.897  0.670  0.639  1.0
  O  O25  1  0.281  0.283  0.526  1.0
  O  O26  1  0.845  0.899  0.188  1.0
  O  O27  1  0.670  0.639  0.897  1.0
  O  O28  1  0.944  0.665  0.111  1.0
  O  O29  1  0.024  0.303  0.571  1.0
  O  O30  1  0.282  0.573  0.649  1.0
  O  O31  1  0.188  0.845  0.899  1.0
[/CIF]
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The structure described by K2Ca2(CO3)3 crystallizes in the trigonal R3 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(4) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form distorted edge-sharing CaO7 pentagonal bipyramids. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(4), and three equivalent O(5) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(4), one O(5), and one O(6) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(2), one Ca(1), one Ca(2), and one C(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), two equivalent Ca(1), and one C(2) atom. In the third O site, O(3) is bonded to two equivalent K(2), one Ca(1), and one C(2) atom to form distorted corner-sharing OK2CaC tetrahedra. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), one Ca(2), and one C(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ca(1), one Ca(2), and one C(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one K(2), two equivalent Ca(1), and one C(1) atom. is represented by the CIF card [CIF]
data_K2Ca2(CO3)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.042
_cell_length_b   8.042
_cell_length_c   8.042
_cell_angle_alpha   107.981
_cell_angle_beta   107.981
_cell_angle_gamma   107.981
_symmetry_Int_Tables_number   1
_cell_volume   421.022
_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
  K  K0  1  0.129  0.129  0.129  1.0
  K  K1  1  0.902  0.444  0.300  1.0
  K  K2  1  0.300  0.902  0.444  1.0
  K  K3  1  0.444  0.300  0.902  1.0
  Ca  Ca4  1  0.975  0.493  0.829  1.0
  Ca  Ca5  1  0.493  0.829  0.975  1.0
  Ca  Ca6  1  0.829  0.975  0.493  1.0
  Ca  Ca7  1  0.553  0.553  0.553  1.0
  C  C8  1  0.583  0.197  0.386  1.0
  C  C9  1  0.067  0.821  0.734  1.0
  C  C10  1  0.734  0.067  0.821  1.0
  C  C11  1  0.821  0.734  0.067  1.0
  C  C12  1  0.197  0.386  0.583  1.0
  C  C13  1  0.386  0.583  0.197  1.0
  O  O14  1  0.639  0.897  0.670  1.0
  O  O15  1  0.899  0.188  0.845  1.0
  O  O16  1  0.665  0.111  0.944  1.0
  O  O17  1  0.526  0.281  0.283  1.0
  O  O18  1  0.649  0.282  0.573  1.0
  O  O19  1  0.571  0.024  0.303  1.0
  O  O20  1  0.283  0.526  0.281  1.0
  O  O21  1  0.111  0.944  0.665  1.0
  O  O22  1  0.303  0.571  0.024  1.0
  O  O23  1  0.573  0.649  0.282  1.0
  O  O24  1  0.897  0.670  0.639  1.0
  O  O25  1  0.281  0.283  0.526  1.0
  O  O26  1  0.845  0.899  0.188  1.0
  O  O27  1  0.670  0.639  0.897  1.0
  O  O28  1  0.944  0.665  0.111  1.0
  O  O29  1  0.024  0.303  0.571  1.0
  O  O30  1  0.282  0.573  0.649  1.0
  O  O31  1  0.188  0.845  0.899  1.0
[/CIF]
.