data_FeCu3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.63
_cell_length_b   4.63
_cell_length_c   4.63
_cell_angle_alpha   144.9
_cell_angle_beta   129.52
_cell_angle_gamma   62.96
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeCu3
_chemical_formula_sum   'Fe1 Cu3'
_cell_volume   43.44
_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  Fe3  1  0.0  0.0  0.0  1.0
  Cu  Cu0  1  0.4  0.0  0.97  1.0
  Cu  Cu1  1  0.0  0.0  0.95  1.0
  Cu  Cu2  1  0.0  0.97  0.97  1.0

data_FeCu3
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.79
_cell_length_b   3.95
_cell_length_c   4.63
_cell_angle_alpha   115.24
_cell_angle_beta   107.55
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeCu3
_chemical_formula_sum   'Fe1 Cu3'
_cell_volume   43.44
_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  Fe0  1  0.0  0.0  0.0  1.0
  Cu  Cu1  1  0.0  0.95  0.95  1.0
  Cu  Cu2  1  0.0  0.97  0.58  1.0
  Cu  Cu3  1  0.03  -0.0  -0.0  1.0

Fe Cu Cu Cu
Fe Cu Cu Cu 0 3 o - - 0 1 o o - 0 2 o o - 1 3 o - o 1 2 o o o 2 3 o - o 
FeCu3 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one FeCu3 cluster. Fe(1) is bonded in a distorted single-bond geometry to one Cu(2) and one Cu(3) atom. The Fe(1)-Cu(2) bond length is 0.25 Å. The Fe(1)-Cu(3) bond length is 0.08 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 1-coordinate geometry to one Cu(2) atom. The Cu(1)-Cu(2) bond length is 1.75 Å. In the second Cu site, Cu(2) is bonded in a 2-coordinate geometry to one Fe(1), one Cu(1), and one Cu(3) atom. The Cu(2)-Cu(3) bond length is 0.24 Å. In the third Cu site, Cu(3) is bonded in a distorted single-bond geometry to one Fe(1) and one Cu(2) atom.