data_AcSb3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.44
_cell_length_b   6.44
_cell_length_c   6.44
_cell_angle_alpha   137.11
_cell_angle_beta   137.11
_cell_angle_gamma   62.26
_symmetry_Int_Tables_number   1
_chemical_formula_structural   AcSb3
_chemical_formula_sum   'Ac1 Sb3'
_cell_volume   122.04
_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
  Ac  Ac0  1  0.0  0.0  0.51  1.0
  Sb  Sb1  1  0.35  0.0  0.75  1.0
  Sb  Sb2  1  0.0  0.35  0.75  1.0
  Sb  Sb3  1  0.0  0.0  0.0  1.0

data_AcSb3
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.66
_cell_length_b   6.66
_cell_length_c   6.44
_cell_angle_alpha   90.0
_cell_angle_beta   121.13
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   AcSb3
_chemical_formula_sum   'Ac2 Sb6'
_cell_volume   244.08
_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
  Ac  Ac0  2  0.0  0.0  0.51  1.0
  Sb  Sb1  4  0.32  0.32  0.4  1.0
  Sb  Sb2  2  0.0  0.0  0.0  1.0

Ac Sb Sb Sb
AcSb3 crystallizes in the monoclinic Cm space group. Ac(1) is bonded in a water-like geometry to two equivalent Sb(1) and two equivalent Sb(2) atoms. Both Ac(1)-Sb(1) bond lengths are 1.55 Å. There is one shorter (3.15 Å) and one longer (3.28 Å) Ac(1)-Sb(2) bond length. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a single-bond geometry to one Ac(1) and one Sb(2) atom. The Sb(1)-Sb(2) bond length is 3.19 Å. In the second Sb site, Sb(2) is bonded in a 4-coordinate geometry to two equivalent Ac(1) and two equivalent Sb(1) atoms.