data_FeB2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.75
_cell_length_b   2.75
_cell_length_c   3.1
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeB2
_chemical_formula_sum   'Fe1 B2'
_cell_volume   23.53
_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
  Fe  Fe2  1  0.0  0.0  0.0  1.0
  B  B0  1  0.0  0.38  0.55  1.0
  B  B1  1  0.38  0.0  0.55  1.0

data_FeB2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.9
_cell_length_b   3.9
_cell_length_c   3.1
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   FeB2
_chemical_formula_sum   'Fe2 B4'
_cell_volume   47.06
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Fe  Fe0  2  0.0  0.0  0.0  1.0
  B  B1  4  0.19  0.19  0.55  1.0

Fe B B
FeB2 crystallizes in the monoclinic Cm space group. Fe(1) is bonded in a 8-coordinate geometry to eight equivalent B(1) atoms. There are a spread of Fe(1)-B(1) bond distances ranging from 1.74-2.42 Å. B(1) is bonded in a 7-coordinate geometry to four equivalent Fe(1) and three equivalent B(1) atoms. There is one shorter (1.47 Å) and two longer (2.01 Å) B(1)-B(1) bond lengths.