The structure described by La2Ni2O5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms. In the second La site, La(2) is bonded in a 7-coordinate geometry to one O(2), one O(3), two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second Ni site, Ni(2) is bonded in a square co-planar geometry to two equivalent O(4) and two equivalent O(5) atoms. In the third Ni site, Ni(3) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 31°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 31°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a 6-coordinate geometry to two equivalent La(1), two equivalent La(2), one Ni(2), and one Ni(3) atom. In the second O site, O(1) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Ni(1), and one Ni(4) atom. In the third O site, O(2) is bonded in a 5-coordinate geometry to one La(2), two equivalent La(1), one Ni(1), and one Ni(3) atom. In the fourth O site, O(3) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Ni(3), and one Ni(4) atom. In the fifth O site, O(4) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Ni(2), and one Ni(4) atom. is represented by the CIF file [CIF]
data_La2Ni2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.588
_cell_length_b   5.588
_cell_length_c   7.525
_cell_angle_alpha   86.509
_cell_angle_beta   86.509
_cell_angle_gamma   89.928
_symmetry_Int_Tables_number   1
_cell_volume   234.094
_cell_formula_units_Z   2
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
  La  La0  1  0.988  0.518  0.248  1.0
  La  La1  1  0.518  0.988  0.748  1.0
  La  La2  1  0.012  0.482  0.752  1.0
  La  La3  1  0.482  0.012  0.252  1.0
  Ni  Ni4  1  0.000  1.000  0.500  1.0
  Ni  Ni5  1  0.000  0.000  0.000  1.0
  Ni  Ni6  1  0.500  0.500  0.000  1.0
  Ni  Ni7  1  0.500  0.500  0.500  1.0
  O  O8  1  0.271  0.192  0.528  1.0
  O  O9  1  0.192  0.271  0.028  1.0
  O  O10  1  0.729  0.808  0.472  1.0
  O  O11  1  0.808  0.729  0.972  1.0
  O  O12  1  0.801  0.265  0.548  1.0
  O  O13  1  0.265  0.801  0.048  1.0
  O  O14  1  0.199  0.735  0.452  1.0
  O  O15  1  0.735  0.199  0.952  1.0
  O  O16  1  0.566  0.434  0.250  1.0
  O  O17  1  0.434  0.566  0.750  1.0
[/CIF]
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The structure described by La2Ni2O5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms. In the second La site, La(2) is bonded in a 7-coordinate geometry to one O(2), one O(3), two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. There are four inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second Ni site, Ni(2) is bonded in a square co-planar geometry to two equivalent O(4) and two equivalent O(5) atoms. In the third Ni site, Ni(3) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 31°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles are 31°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a 6-coordinate geometry to two equivalent La(1), two equivalent La(2), one Ni(2), and one Ni(3) atom. In the second O site, O(1) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Ni(1), and one Ni(4) atom. In the third O site, O(2) is bonded in a 5-coordinate geometry to one La(2), two equivalent La(1), one Ni(1), and one Ni(3) atom. In the fourth O site, O(3) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Ni(3), and one Ni(4) atom. In the fifth O site, O(4) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Ni(2), and one Ni(4) atom. is represented by the CIF file [CIF]
data_La2Ni2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.588
_cell_length_b   5.588
_cell_length_c   7.525
_cell_angle_alpha   86.509
_cell_angle_beta   86.509
_cell_angle_gamma   89.928
_symmetry_Int_Tables_number   1
_cell_volume   234.094
_cell_formula_units_Z   2
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
  La  La0  1  0.988  0.518  0.248  1.0
  La  La1  1  0.518  0.988  0.748  1.0
  La  La2  1  0.012  0.482  0.752  1.0
  La  La3  1  0.482  0.012  0.252  1.0
  Ni  Ni4  1  0.000  1.000  0.500  1.0
  Ni  Ni5  1  0.000  0.000  0.000  1.0
  Ni  Ni6  1  0.500  0.500  0.000  1.0
  Ni  Ni7  1  0.500  0.500  0.500  1.0
  O  O8  1  0.271  0.192  0.528  1.0
  O  O9  1  0.192  0.271  0.028  1.0
  O  O10  1  0.729  0.808  0.472  1.0
  O  O11  1  0.808  0.729  0.972  1.0
  O  O12  1  0.801  0.265  0.548  1.0
  O  O13  1  0.265  0.801  0.048  1.0
  O  O14  1  0.199  0.735  0.452  1.0
  O  O15  1  0.735  0.199  0.952  1.0
  O  O16  1  0.566  0.434  0.250  1.0
  O  O17  1  0.434  0.566  0.750  1.0
[/CIF]
.