data_YbF3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.08
_cell_length_b   4.08
_cell_length_c   4.08
_cell_angle_alpha   126.7
_cell_angle_beta   126.7
_cell_angle_gamma   78.74
_symmetry_Int_Tables_number   1
_chemical_formula_structural   YbF3
_chemical_formula_sum   'Yb1 F3'
_cell_volume   42.21
_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
  Yb  Yb0  1  0.0  0.0  0.15  1.0
  F  F1  1  0.83  0.0  0.58  1.0
  F  F2  1  0.0  0.83  0.58  1.0
  F  F3  1  0.0  0.0  0.0  1.0

data_YbF3
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.17
_cell_length_b   5.17
_cell_length_c   4.08
_cell_angle_alpha   90.0
_cell_angle_beta   129.37
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   YbF3
_chemical_formula_sum   'Yb2 F6'
_cell_volume   84.42
_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
  Yb  Yb0  2  0.35  0.5  0.85  1.0
  F  F1  4  0.34  0.09  0.25  1.0
  F  F2  2  0.0  0.0  0.0  1.0

Yb F F F
YbF3 crystallizes in the monoclinic Cm space group. Yb(1) is bonded in a single-bond geometry to one F(2) and four equivalent F(1) atoms. The Yb(1)-F(2) bond length is 0.62 Å. There are two shorter (2.21 Å) and two longer (2.73 Å) Yb(1)-F(1) bond lengths. There are two inequivalent F sites. In the first F site, F(1) is bonded in a 4-coordinate geometry to two equivalent Yb(1), one F(1), and one F(2) atom. The F(1)-F(1) bond length is 0.88 Å. The F(1)-F(2) bond length is 1.43 Å. In the second F site, F(2) is bonded in a single-bond geometry to one Yb(1) and two equivalent F(1) atoms.