The material described by MgCr4(PO4)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(11), one O(2), one O(3), one O(5), and one O(8) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 6-coordinate geometry to one O(1), one O(15), one O(16), one O(3), one O(4), and one O(5) atom. In the second Cr site, Cr(2) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted CrO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. In the third Cr site, Cr(3) is bonded to one O(10), one O(11), one O(12), one O(13), one O(15), and one O(9) atom to form distorted CrO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  an edgeedge with one P(3)O4 tetrahedra, and  an edgeedge with one Cr(4)O5 trigonal bipyramid. In the fourth Cr site, Cr(4) is bonded to one O(1), one O(12), one O(13), one O(14), and one O(16) atom to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one Cr(3)O6 octahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(13), one O(2), and one O(3) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Cr(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 39-51°. In the second P site, P(2) is bonded to one O(5), one O(6), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and  an edgeedge with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-46°. In the third P site, P(3) is bonded to one O(10), one O(11), one O(12), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra,  a cornercorner with one Cr(4)O5 trigonal bipyramid, and  an edgeedge with one Cr(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-47°. In the fourth P site, P(4) is bonded to one O(14), one O(15), one O(16), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Cr(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-47°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(4), and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Cr(2), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(2), and one P(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Cr(1), one Cr(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a water-like geometry to one Cr(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Cr(2) and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Cr(3) and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 120 degrees geometry to one Cr(3) and one P(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Cr(3), and one P(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal non-coplanar geometry to one Cr(3), one Cr(4), and one P(3) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Cr(3), one Cr(4), and one P(1) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Cr(4) and one P(4) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(3), and one P(4) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(4), and one P(4) atom. is represented by the CIF card [CIF]
data_MgCr4(PO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.578
_cell_length_b   5.727
_cell_length_c   6.538
_cell_angle_alpha   100.463
_cell_angle_beta   109.498
_cell_angle_gamma   78.486
_symmetry_Int_Tables_number   1
_cell_volume   328.681
_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
  Mg  Mg0  1  0.312  0.005  0.124  1.0
  Cr  Cr1  1  0.045  0.282  0.325  1.0
  Cr  Cr2  1  0.312  0.873  0.579  1.0
  Cr  Cr3  1  0.690  0.125  0.413  1.0
  Cr  Cr4  1  0.931  0.696  0.676  1.0
  P  P5  1  0.053  0.169  0.796  1.0
  P  P6  1  0.425  0.299  0.645  1.0
  P  P7  1  0.574  0.700  0.337  1.0
  P  P8  1  0.950  0.815  0.211  1.0
  O  O9  1  0.060  0.360  0.662  1.0
  O  O10  1  0.181  0.949  0.783  1.0
  O  O11  1  0.104  0.250  0.044  1.0
  O  O12  1  0.112  0.896  0.304  1.0
  O  O13  1  0.310  0.179  0.431  1.0
  O  O14  1  0.435  0.115  0.802  1.0
  O  O15  1  0.358  0.558  0.710  1.0
  O  O16  1  0.414  0.715  0.358  1.0
  O  O17  1  0.573  0.298  0.603  1.0
  O  O18  1  0.635  0.443  0.266  1.0
  O  O19  1  0.541  0.904  0.181  1.0
  O  O20  1  0.692  0.818  0.538  1.0
  O  O21  1  0.897  0.092  0.703  1.0
  O  O22  1  0.920  0.704  0.976  1.0
  O  O23  1  0.841  0.044  0.248  1.0
  O  O24  1  0.947  0.630  0.357  1.0
[/CIF]
.
The material described by MgCr4(PO4)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(11), one O(2), one O(3), one O(5), and one O(8) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a 6-coordinate geometry to one O(1), one O(15), one O(16), one O(3), one O(4), and one O(5) atom. In the second Cr site, Cr(2) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted CrO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. In the third Cr site, Cr(3) is bonded to one O(10), one O(11), one O(12), one O(13), one O(15), and one O(9) atom to form distorted CrO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra,  an edgeedge with one P(3)O4 tetrahedra, and  an edgeedge with one Cr(4)O5 trigonal bipyramid. In the fourth Cr site, Cr(4) is bonded to one O(1), one O(12), one O(13), one O(14), and one O(16) atom to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one Cr(3)O6 octahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(13), one O(2), and one O(3) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Cr(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 39-51°. In the second P site, P(2) is bonded to one O(5), one O(6), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and  an edgeedge with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-46°. In the third P site, P(3) is bonded to one O(10), one O(11), one O(12), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra,  a cornercorner with one Cr(4)O5 trigonal bipyramid, and  an edgeedge with one Cr(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-47°. In the fourth P site, P(4) is bonded to one O(14), one O(15), one O(16), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Cr(4)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-47°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(4), and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Cr(2), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(2), and one P(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Cr(1), one Cr(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a water-like geometry to one Cr(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Cr(2) and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Cr(3) and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 120 degrees geometry to one Cr(3) and one P(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Cr(3), and one P(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal non-coplanar geometry to one Cr(3), one Cr(4), and one P(3) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Cr(3), one Cr(4), and one P(1) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Cr(4) and one P(4) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(3), and one P(4) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(4), and one P(4) atom. is represented by the CIF card [CIF]
data_MgCr4(PO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.578
_cell_length_b   5.727
_cell_length_c   6.538
_cell_angle_alpha   100.463
_cell_angle_beta   109.498
_cell_angle_gamma   78.486
_symmetry_Int_Tables_number   1
_cell_volume   328.681
_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
  Mg  Mg0  1  0.312  0.005  0.124  1.0
  Cr  Cr1  1  0.045  0.282  0.325  1.0
  Cr  Cr2  1  0.312  0.873  0.579  1.0
  Cr  Cr3  1  0.690  0.125  0.413  1.0
  Cr  Cr4  1  0.931  0.696  0.676  1.0
  P  P5  1  0.053  0.169  0.796  1.0
  P  P6  1  0.425  0.299  0.645  1.0
  P  P7  1  0.574  0.700  0.337  1.0
  P  P8  1  0.950  0.815  0.211  1.0
  O  O9  1  0.060  0.360  0.662  1.0
  O  O10  1  0.181  0.949  0.783  1.0
  O  O11  1  0.104  0.250  0.044  1.0
  O  O12  1  0.112  0.896  0.304  1.0
  O  O13  1  0.310  0.179  0.431  1.0
  O  O14  1  0.435  0.115  0.802  1.0
  O  O15  1  0.358  0.558  0.710  1.0
  O  O16  1  0.414  0.715  0.358  1.0
  O  O17  1  0.573  0.298  0.603  1.0
  O  O18  1  0.635  0.443  0.266  1.0
  O  O19  1  0.541  0.904  0.181  1.0
  O  O20  1  0.692  0.818  0.538  1.0
  O  O21  1  0.897  0.092  0.703  1.0
  O  O22  1  0.920  0.704  0.976  1.0
  O  O23  1  0.841  0.044  0.248  1.0
  O  O24  1  0.947  0.630  0.357  1.0
[/CIF]
.