The material structure described by Cr4(PO4)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and  an edgeedge with one Cr(3)O6 octahedra. In the second Cr site, Cr(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(3) and two equivalent O(6) atoms. In the third Cr site, Cr(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Cr(3)O6 octahedra and corners with four equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-57°. In the second P site, P(2) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Cr(3)O6 octahedra and corners with four equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-58°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Cr(1) and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one P(1) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one P(1) atom. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one P(2) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one P(2) atom. is represented by the CIF card [CIF]
data_Cr4(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.853
_cell_length_b   8.853
_cell_length_c   6.810
_cell_angle_alpha   71.480
_cell_angle_beta   71.480
_cell_angle_gamma   90.875
_symmetry_Int_Tables_number   1
_cell_volume   475.810
_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
  Cr  Cr0  1  0.937  0.621  0.132  1.0
  Cr  Cr1  1  0.063  0.379  0.868  1.0
  Cr  Cr2  1  0.503  0.497  0.250  1.0
  Cr  Cr3  1  0.746  0.254  0.750  1.0
  Cr  Cr4  1  0.621  0.937  0.632  1.0
  Cr  Cr5  1  0.497  0.503  0.750  1.0
  Cr  Cr6  1  0.379  0.063  0.368  1.0
  Cr  Cr7  1  0.254  0.746  0.250  1.0
  P  P8  1  0.127  0.352  0.375  1.0
  P  P9  1  0.720  0.280  0.250  1.0
  P  P10  1  0.873  0.648  0.625  1.0
  P  P11  1  0.280  0.720  0.750  1.0
  P  P12  1  0.648  0.873  0.125  1.0
  P  P13  1  0.352  0.127  0.875  1.0
  O  O14  1  0.798  0.799  0.634  1.0
  O  O15  1  0.328  0.002  0.106  1.0
  O  O16  1  0.540  0.268  0.251  1.0
  O  O17  1  0.833  0.259  0.040  1.0
  O  O18  1  0.732  0.460  0.249  1.0
  O  O19  1  0.045  0.411  0.195  1.0
  O  O20  1  0.737  0.507  0.675  1.0
  O  O21  1  0.002  0.328  0.606  1.0
  O  O22  1  0.268  0.540  0.751  1.0
  O  O23  1  0.672  0.998  0.894  1.0
  O  O24  1  0.201  0.202  0.866  1.0
  O  O25  1  0.493  0.263  0.825  1.0
  O  O26  1  0.202  0.201  0.366  1.0
  O  O27  1  0.259  0.833  0.540  1.0
  O  O28  1  0.799  0.798  0.134  1.0
  O  O29  1  0.460  0.732  0.749  1.0
  O  O30  1  0.741  0.167  0.460  1.0
  O  O31  1  0.167  0.741  0.960  1.0
  O  O32  1  0.507  0.737  0.175  1.0
  O  O33  1  0.589  0.955  0.305  1.0
  O  O34  1  0.998  0.672  0.394  1.0
  O  O35  1  0.263  0.493  0.325  1.0
  O  O36  1  0.955  0.589  0.805  1.0
  O  O37  1  0.411  0.045  0.695  1.0
[/CIF]
.
The material structure described by Cr4(PO4)3 crystallizes in the monoclinic C2/c space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and  an edgeedge with one Cr(3)O6 octahedra. In the second Cr site, Cr(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(3) and two equivalent O(6) atoms. In the third Cr site, Cr(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Cr(3)O6 octahedra and corners with four equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-57°. In the second P site, P(2) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent Cr(3)O6 octahedra and corners with four equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-58°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Cr(1) and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one P(1) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Cr(1) and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one P(1) atom. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one P(2) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one P(2) atom. is represented by the CIF card [CIF]
data_Cr4(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.853
_cell_length_b   8.853
_cell_length_c   6.810
_cell_angle_alpha   71.480
_cell_angle_beta   71.480
_cell_angle_gamma   90.875
_symmetry_Int_Tables_number   1
_cell_volume   475.810
_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
  Cr  Cr0  1  0.937  0.621  0.132  1.0
  Cr  Cr1  1  0.063  0.379  0.868  1.0
  Cr  Cr2  1  0.503  0.497  0.250  1.0
  Cr  Cr3  1  0.746  0.254  0.750  1.0
  Cr  Cr4  1  0.621  0.937  0.632  1.0
  Cr  Cr5  1  0.497  0.503  0.750  1.0
  Cr  Cr6  1  0.379  0.063  0.368  1.0
  Cr  Cr7  1  0.254  0.746  0.250  1.0
  P  P8  1  0.127  0.352  0.375  1.0
  P  P9  1  0.720  0.280  0.250  1.0
  P  P10  1  0.873  0.648  0.625  1.0
  P  P11  1  0.280  0.720  0.750  1.0
  P  P12  1  0.648  0.873  0.125  1.0
  P  P13  1  0.352  0.127  0.875  1.0
  O  O14  1  0.798  0.799  0.634  1.0
  O  O15  1  0.328  0.002  0.106  1.0
  O  O16  1  0.540  0.268  0.251  1.0
  O  O17  1  0.833  0.259  0.040  1.0
  O  O18  1  0.732  0.460  0.249  1.0
  O  O19  1  0.045  0.411  0.195  1.0
  O  O20  1  0.737  0.507  0.675  1.0
  O  O21  1  0.002  0.328  0.606  1.0
  O  O22  1  0.268  0.540  0.751  1.0
  O  O23  1  0.672  0.998  0.894  1.0
  O  O24  1  0.201  0.202  0.866  1.0
  O  O25  1  0.493  0.263  0.825  1.0
  O  O26  1  0.202  0.201  0.366  1.0
  O  O27  1  0.259  0.833  0.540  1.0
  O  O28  1  0.799  0.798  0.134  1.0
  O  O29  1  0.460  0.732  0.749  1.0
  O  O30  1  0.741  0.167  0.460  1.0
  O  O31  1  0.167  0.741  0.960  1.0
  O  O32  1  0.507  0.737  0.175  1.0
  O  O33  1  0.589  0.955  0.305  1.0
  O  O34  1  0.998  0.672  0.394  1.0
  O  O35  1  0.263  0.493  0.325  1.0
  O  O36  1  0.955  0.589  0.805  1.0
  O  O37  1  0.411  0.045  0.695  1.0
[/CIF]
.