The material described by Ca4MgB4(CO9)2 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms. Mg(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent B(2)O4 tetrahedra, corners with four equivalent B(1)O4 tetrahedra, and edges with two equivalent B(2)O4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent B(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 65°. In the second B site, B(2) is bonded to one O(1), one O(5), and two equivalent O(2) atoms to form BO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent B(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. C(1) is bonded in a trigonal planar geometry to one O(6) and two equivalent O(4) atoms. There are six inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Ca(1) and one C(1) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Ca(1) and one B(2) atom. In the third O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ca(1) and one C(1) atom. In the fourth O site, O(1) is bonded to two equivalent Ca(1), one Mg(1), and one B(2) atom to form distorted corner-sharing OCa2MgB tetrahedra. In the fifth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one B(1), and one B(2) atom. In the sixth O site, O(3) is bonded in a distorted single-bond geometry to one Ca(1) and one B(1) atom. is represented by the CIF file [CIF]
data_Ca4MgB4(CO9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.081
_cell_length_b   10.081
_cell_length_c   4.571
_cell_angle_alpha   77.045
_cell_angle_beta   77.045
_cell_angle_gamma   46.627
_symmetry_Int_Tables_number   1
_cell_volume   327.459
_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
  Ca  Ca0  1  0.392  0.923  0.854  1.0
  Ca  Ca1  1  0.923  0.392  0.854  1.0
  Ca  Ca2  1  0.608  0.077  0.146  1.0
  Ca  Ca3  1  0.077  0.608  0.146  1.0
  Mg  Mg4  1  0.000  0.000  0.000  1.0
  B  B5  1  0.258  0.742  0.500  1.0
  B  B6  1  0.742  0.258  0.500  1.0
  B  B7  1  0.097  0.097  0.443  1.0
  B  B8  1  0.903  0.903  0.557  1.0
  C  C9  1  0.694  0.694  0.369  1.0
  C  C10  1  0.306  0.306  0.631  1.0
  O  O11  1  0.097  0.097  0.132  1.0
  O  O12  1  0.903  0.903  0.868  1.0
  O  O13  1  0.204  0.901  0.624  1.0
  O  O14  1  0.901  0.204  0.624  1.0
  O  O15  1  0.796  0.099  0.376  1.0
  O  O16  1  0.099  0.796  0.376  1.0
  O  O17  1  0.398  0.693  0.248  1.0
  O  O18  1  0.693  0.398  0.248  1.0
  O  O19  1  0.602  0.307  0.752  1.0
  O  O20  1  0.307  0.602  0.752  1.0
  O  O21  1  0.572  0.854  0.230  1.0
  O  O22  1  0.854  0.572  0.230  1.0
  O  O23  1  0.428  0.146  0.770  1.0
  O  O24  1  0.146  0.428  0.770  1.0
  O  O25  1  0.167  0.167  0.511  1.0
  O  O26  1  0.833  0.833  0.489  1.0
  O  O27  1  0.657  0.657  0.645  1.0
  O  O28  1  0.343  0.343  0.355  1.0
[/CIF]
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The material described by Ca4MgB4(CO9)2 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms. Mg(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent B(2)O4 tetrahedra, corners with four equivalent B(1)O4 tetrahedra, and edges with two equivalent B(2)O4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent B(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 65°. In the second B site, B(2) is bonded to one O(1), one O(5), and two equivalent O(2) atoms to form BO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent B(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. C(1) is bonded in a trigonal planar geometry to one O(6) and two equivalent O(4) atoms. There are six inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Ca(1) and one C(1) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Ca(1) and one B(2) atom. In the third O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ca(1) and one C(1) atom. In the fourth O site, O(1) is bonded to two equivalent Ca(1), one Mg(1), and one B(2) atom to form distorted corner-sharing OCa2MgB tetrahedra. In the fifth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one B(1), and one B(2) atom. In the sixth O site, O(3) is bonded in a distorted single-bond geometry to one Ca(1) and one B(1) atom. is represented by the CIF file [CIF]
data_Ca4MgB4(CO9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.081
_cell_length_b   10.081
_cell_length_c   4.571
_cell_angle_alpha   77.045
_cell_angle_beta   77.045
_cell_angle_gamma   46.627
_symmetry_Int_Tables_number   1
_cell_volume   327.459
_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
  Ca  Ca0  1  0.392  0.923  0.854  1.0
  Ca  Ca1  1  0.923  0.392  0.854  1.0
  Ca  Ca2  1  0.608  0.077  0.146  1.0
  Ca  Ca3  1  0.077  0.608  0.146  1.0
  Mg  Mg4  1  0.000  0.000  0.000  1.0
  B  B5  1  0.258  0.742  0.500  1.0
  B  B6  1  0.742  0.258  0.500  1.0
  B  B7  1  0.097  0.097  0.443  1.0
  B  B8  1  0.903  0.903  0.557  1.0
  C  C9  1  0.694  0.694  0.369  1.0
  C  C10  1  0.306  0.306  0.631  1.0
  O  O11  1  0.097  0.097  0.132  1.0
  O  O12  1  0.903  0.903  0.868  1.0
  O  O13  1  0.204  0.901  0.624  1.0
  O  O14  1  0.901  0.204  0.624  1.0
  O  O15  1  0.796  0.099  0.376  1.0
  O  O16  1  0.099  0.796  0.376  1.0
  O  O17  1  0.398  0.693  0.248  1.0
  O  O18  1  0.693  0.398  0.248  1.0
  O  O19  1  0.602  0.307  0.752  1.0
  O  O20  1  0.307  0.602  0.752  1.0
  O  O21  1  0.572  0.854  0.230  1.0
  O  O22  1  0.854  0.572  0.230  1.0
  O  O23  1  0.428  0.146  0.770  1.0
  O  O24  1  0.146  0.428  0.770  1.0
  O  O25  1  0.167  0.167  0.511  1.0
  O  O26  1  0.833  0.833  0.489  1.0
  O  O27  1  0.657  0.657  0.645  1.0
  O  O28  1  0.343  0.343  0.355  1.0
[/CIF]
.