The structure described by MgB2C2 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent B(3), four equivalent B(1), two equivalent C(3), and four equivalent C(1) atoms. In the second Mg site, Mg(2) is bonded in a 12-coordinate geometry to two equivalent B(1), two equivalent B(2), two equivalent B(3), two equivalent C(1), two equivalent C(2), and two equivalent C(3) atoms. There are three inequivalent B sites. In the first B site, B(1) is bonded in a distorted trigonal planar geometry to one Mg(2), two equivalent Mg(1), one C(1), one C(2), and one C(3) atom. In the second B site, B(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2), one C(2), and two equivalent C(1) atoms. In the third B site, B(3) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1), two equivalent Mg(2), one C(3), and two equivalent C(1) atoms. There are three inequivalent C sites. In the first C site, C(3) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1), two equivalent Mg(2), one B(3), and two equivalent B(1) atoms. In the second C site, C(1) is bonded in a distorted trigonal planar geometry to one Mg(2), two equivalent Mg(1), one B(1), one B(2), and one B(3) atom. In the third C site, C(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2), one B(2), and two equivalent B(1) atoms. is represented by the CIF card [CIF]
data_Mg(BC)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.200
_cell_length_b   7.200
_cell_length_c   7.407
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   98.177
_symmetry_Int_Tables_number   1
_cell_volume   380.088
_cell_formula_units_Z   8
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  0.722  0.722  0.009  1.0
  Mg  Mg1  1  0.778  0.778  0.509  1.0
  Mg  Mg2  1  0.222  0.222  0.491  1.0
  Mg  Mg3  1  0.278  0.278  0.991  1.0
  Mg  Mg4  1  0.348  0.652  0.500  1.0
  Mg  Mg5  1  0.152  0.848  0.000  1.0
  Mg  Mg6  1  0.652  0.348  0.500  1.0
  Mg  Mg7  1  0.848  0.152  0.000  1.0
  B  B8  1  0.787  0.532  0.755  1.0
  B  B9  1  0.468  0.213  0.245  1.0
  B  B10  1  0.032  0.287  0.745  1.0
  B  B11  1  0.713  0.968  0.255  1.0
  B  B12  1  0.532  0.787  0.755  1.0
  B  B13  1  0.968  0.713  0.255  1.0
  B  B14  1  0.287  0.032  0.745  1.0
  B  B15  1  0.213  0.468  0.245  1.0
  B  B16  1  0.844  0.344  0.250  1.0
  B  B17  1  0.656  0.156  0.750  1.0
  B  B18  1  0.156  0.656  0.750  1.0
  B  B19  1  0.344  0.844  0.250  1.0
  B  B20  1  0.588  0.588  0.275  1.0
  B  B21  1  0.912  0.912  0.775  1.0
  B  B22  1  0.088  0.088  0.225  1.0
  B  B23  1  0.412  0.412  0.725  1.0
  C  C24  1  0.050  0.299  0.224  1.0
  C  C25  1  0.450  0.201  0.724  1.0
  C  C26  1  0.799  0.550  0.276  1.0
  C  C27  1  0.701  0.950  0.776  1.0
  C  C28  1  0.299  0.050  0.224  1.0
  C  C29  1  0.950  0.701  0.776  1.0
  C  C30  1  0.550  0.799  0.276  1.0
  C  C31  1  0.201  0.450  0.724  1.0
  C  C32  1  0.677  0.177  0.250  1.0
  C  C33  1  0.823  0.323  0.750  1.0
  C  C34  1  0.323  0.823  0.750  1.0
  C  C35  1  0.177  0.677  0.250  1.0
  C  C36  1  0.920  0.920  0.230  1.0
  C  C37  1  0.580  0.580  0.730  1.0
  C  C38  1  0.420  0.420  0.270  1.0
  C  C39  1  0.080  0.080  0.770  1.0
[/CIF]
.
The structure described by MgB2C2 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent B(3), four equivalent B(1), two equivalent C(3), and four equivalent C(1) atoms. In the second Mg site, Mg(2) is bonded in a 12-coordinate geometry to two equivalent B(1), two equivalent B(2), two equivalent B(3), two equivalent C(1), two equivalent C(2), and two equivalent C(3) atoms. There are three inequivalent B sites. In the first B site, B(1) is bonded in a distorted trigonal planar geometry to one Mg(2), two equivalent Mg(1), one C(1), one C(2), and one C(3) atom. In the second B site, B(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2), one C(2), and two equivalent C(1) atoms. In the third B site, B(3) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1), two equivalent Mg(2), one C(3), and two equivalent C(1) atoms. There are three inequivalent C sites. In the first C site, C(3) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1), two equivalent Mg(2), one B(3), and two equivalent B(1) atoms. In the second C site, C(1) is bonded in a distorted trigonal planar geometry to one Mg(2), two equivalent Mg(1), one B(1), one B(2), and one B(3) atom. In the third C site, C(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2), one B(2), and two equivalent B(1) atoms. is represented by the CIF card [CIF]
data_Mg(BC)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.200
_cell_length_b   7.200
_cell_length_c   7.407
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   98.177
_symmetry_Int_Tables_number   1
_cell_volume   380.088
_cell_formula_units_Z   8
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  0.722  0.722  0.009  1.0
  Mg  Mg1  1  0.778  0.778  0.509  1.0
  Mg  Mg2  1  0.222  0.222  0.491  1.0
  Mg  Mg3  1  0.278  0.278  0.991  1.0
  Mg  Mg4  1  0.348  0.652  0.500  1.0
  Mg  Mg5  1  0.152  0.848  0.000  1.0
  Mg  Mg6  1  0.652  0.348  0.500  1.0
  Mg  Mg7  1  0.848  0.152  0.000  1.0
  B  B8  1  0.787  0.532  0.755  1.0
  B  B9  1  0.468  0.213  0.245  1.0
  B  B10  1  0.032  0.287  0.745  1.0
  B  B11  1  0.713  0.968  0.255  1.0
  B  B12  1  0.532  0.787  0.755  1.0
  B  B13  1  0.968  0.713  0.255  1.0
  B  B14  1  0.287  0.032  0.745  1.0
  B  B15  1  0.213  0.468  0.245  1.0
  B  B16  1  0.844  0.344  0.250  1.0
  B  B17  1  0.656  0.156  0.750  1.0
  B  B18  1  0.156  0.656  0.750  1.0
  B  B19  1  0.344  0.844  0.250  1.0
  B  B20  1  0.588  0.588  0.275  1.0
  B  B21  1  0.912  0.912  0.775  1.0
  B  B22  1  0.088  0.088  0.225  1.0
  B  B23  1  0.412  0.412  0.725  1.0
  C  C24  1  0.050  0.299  0.224  1.0
  C  C25  1  0.450  0.201  0.724  1.0
  C  C26  1  0.799  0.550  0.276  1.0
  C  C27  1  0.701  0.950  0.776  1.0
  C  C28  1  0.299  0.050  0.224  1.0
  C  C29  1  0.950  0.701  0.776  1.0
  C  C30  1  0.550  0.799  0.276  1.0
  C  C31  1  0.201  0.450  0.724  1.0
  C  C32  1  0.677  0.177  0.250  1.0
  C  C33  1  0.823  0.323  0.750  1.0
  C  C34  1  0.323  0.823  0.750  1.0
  C  C35  1  0.177  0.677  0.250  1.0
  C  C36  1  0.920  0.920  0.230  1.0
  C  C37  1  0.580  0.580  0.730  1.0
  C  C38  1  0.420  0.420  0.270  1.0
  C  C39  1  0.080  0.080  0.770  1.0
[/CIF]
.