The compound described by BC7 is beta beryllia-like structured and crystallizes in the trigonal R3m space group. B(1) is bonded to one C(2) and three equivalent C(4) atoms to form BC4 tetrahedra that share corners with three equivalent C(3)C4 tetrahedra, corners with three equivalent C(5)C4 tetrahedra, and corners with six equivalent B(1)C4 tetrahedra. There are seven inequivalent C sites. In the first C site, C(1) is bonded to one C(7) and three equivalent C(3) atoms to form CC4 tetrahedra that share corners with three equivalent C(4)B3C tetrahedra, corners with three equivalent C(6)C4 tetrahedra, and corners with six equivalent C(1)C4 tetrahedra. In the second C site, C(2) is bonded to one B(1) and three equivalent C(5) atoms to form CBC3 tetrahedra that share corners with three equivalent C(4)B3C tetrahedra, corners with three equivalent C(6)C4 tetrahedra, and corners with six equivalent C(2)BC3 tetrahedra. In the third C site, C(3) is bonded to one C(4) and three equivalent C(1) atoms to form CC4 tetrahedra that share corners with three equivalent B(1)C4 tetrahedra, corners with three equivalent C(7)C4 tetrahedra, and corners with six equivalent C(3)C4 tetrahedra. In the fourth C site, C(4) is bonded to three equivalent B(1) and one C(3) atom to form distorted CB3C tetrahedra that share corners with three equivalent C(2)BC3 tetrahedra, corners with three equivalent C(1)C4 tetrahedra, and corners with six equivalent C(4)B3C tetrahedra. In the fifth C site, C(5) is bonded to one C(6) and three equivalent C(2) atoms to form CC4 tetrahedra that share corners with three equivalent B(1)C4 tetrahedra, corners with three equivalent C(7)C4 tetrahedra, and corners with six equivalent C(5)C4 tetrahedra. In the sixth C site, C(6) is bonded to one C(5) and three equivalent C(7) atoms to form CC4 tetrahedra that share corners with three equivalent C(2)BC3 tetrahedra, corners with three equivalent C(1)C4 tetrahedra, and corners with six equivalent C(6)C4 tetrahedra. In the seventh C site, C(7) is bonded to one C(1) and three equivalent C(6) atoms to form corner-sharing CC4 tetrahedra. is represented by the CIF card [CIF]
data_BC7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.642
_cell_length_b   8.642
_cell_length_c   8.642
_cell_angle_alpha   16.884
_cell_angle_beta   16.884
_cell_angle_gamma   16.884
_symmetry_Int_Tables_number   1
_cell_volume   47.494
_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
  B  B0  1  0.802  0.802  0.802  1.0
  C  C1  1  0.911  0.911  0.911  1.0
  C  C2  1  0.739  0.739  0.739  1.0
  C  C3  1  0.556  0.556  0.556  1.0
  C  C4  1  0.497  0.497  0.497  1.0
  C  C5  1  0.385  0.385  0.385  1.0
  C  C6  1  0.325  0.325  0.325  1.0
  C  C7  1  0.971  0.971  0.971  1.0
[/CIF]
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The compound described by BC7 is beta beryllia-like structured and crystallizes in the trigonal R3m space group. B(1) is bonded to one C(2) and three equivalent C(4) atoms to form BC4 tetrahedra that share corners with three equivalent C(3)C4 tetrahedra, corners with three equivalent C(5)C4 tetrahedra, and corners with six equivalent B(1)C4 tetrahedra. There are seven inequivalent C sites. In the first C site, C(1) is bonded to one C(7) and three equivalent C(3) atoms to form CC4 tetrahedra that share corners with three equivalent C(4)B3C tetrahedra, corners with three equivalent C(6)C4 tetrahedra, and corners with six equivalent C(1)C4 tetrahedra. In the second C site, C(2) is bonded to one B(1) and three equivalent C(5) atoms to form CBC3 tetrahedra that share corners with three equivalent C(4)B3C tetrahedra, corners with three equivalent C(6)C4 tetrahedra, and corners with six equivalent C(2)BC3 tetrahedra. In the third C site, C(3) is bonded to one C(4) and three equivalent C(1) atoms to form CC4 tetrahedra that share corners with three equivalent B(1)C4 tetrahedra, corners with three equivalent C(7)C4 tetrahedra, and corners with six equivalent C(3)C4 tetrahedra. In the fourth C site, C(4) is bonded to three equivalent B(1) and one C(3) atom to form distorted CB3C tetrahedra that share corners with three equivalent C(2)BC3 tetrahedra, corners with three equivalent C(1)C4 tetrahedra, and corners with six equivalent C(4)B3C tetrahedra. In the fifth C site, C(5) is bonded to one C(6) and three equivalent C(2) atoms to form CC4 tetrahedra that share corners with three equivalent B(1)C4 tetrahedra, corners with three equivalent C(7)C4 tetrahedra, and corners with six equivalent C(5)C4 tetrahedra. In the sixth C site, C(6) is bonded to one C(5) and three equivalent C(7) atoms to form CC4 tetrahedra that share corners with three equivalent C(2)BC3 tetrahedra, corners with three equivalent C(1)C4 tetrahedra, and corners with six equivalent C(6)C4 tetrahedra. In the seventh C site, C(7) is bonded to one C(1) and three equivalent C(6) atoms to form corner-sharing CC4 tetrahedra. is represented by the CIF card [CIF]
data_BC7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.642
_cell_length_b   8.642
_cell_length_c   8.642
_cell_angle_alpha   16.884
_cell_angle_beta   16.884
_cell_angle_gamma   16.884
_symmetry_Int_Tables_number   1
_cell_volume   47.494
_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
  B  B0  1  0.802  0.802  0.802  1.0
  C  C1  1  0.911  0.911  0.911  1.0
  C  C2  1  0.739  0.739  0.739  1.0
  C  C3  1  0.556  0.556  0.556  1.0
  C  C4  1  0.497  0.497  0.497  1.0
  C  C5  1  0.385  0.385  0.385  1.0
  C  C6  1  0.325  0.325  0.325  1.0
  C  C7  1  0.971  0.971  0.971  1.0
[/CIF]
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