The crystal structure described by MgCr4(PbO4)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(13), one O(3), and one O(8) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(12), one O(16), and one O(5) atom to form CrO4 tetrahedra that share  a cornercorner with one Pb(2)O5 square pyramid. In the second Cr site, Cr(2) is bonded to one O(13), one O(4), one O(8), and one O(9) atom to form CrO4 tetrahedra that share  a cornercorner with one Pb(2)O5 square pyramid. In the third Cr site, Cr(3) is bonded to one O(11), one O(15), one O(2), and one O(6) atom to form CrO4 tetrahedra that share corners with two equivalent Pb(2)O5 square pyramids. In the fourth Cr site, Cr(4) is bonded to one O(10), one O(14), one O(3), and one O(7) atom to form CrO4 tetrahedra that share  a cornercorner with one Pb(2)O5 square pyramid. There are four inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a 6-coordinate geometry to one O(1), one O(12), one O(15), one O(4), one O(5), and one O(7) atom. In the second Pb site, Pb(2) is bonded to one O(11), one O(16), one O(3), one O(6), and one O(8) atom to form PbO5 square pyramids that share  a cornercorner with one Cr(1)O4 tetrahedra,  a cornercorner with one Cr(2)O4 tetrahedra,  a cornercorner with one Cr(4)O4 tetrahedra, and corners with two equivalent Cr(3)O4 tetrahedra. In the third Pb site, Pb(3) is bonded in a 4-coordinate geometry to one O(13), one O(3), one O(5), and one O(7) atom. In the fourth Pb site, Pb(4) is bonded in a 4-coordinate geometry to one O(14), one O(6), one O(8), and one O(9) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Cr(1) and one Pb(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Cr(3) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(4), one Pb(2), and one Pb(3) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Cr(2) and one Pb(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Cr(1), one Pb(1), and one Pb(3) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Cr(3), one Pb(2), and one Pb(4) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Cr(4), one Pb(1), and one Pb(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(2), one Pb(2), and one Pb(4) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one Cr(2) and one Pb(4) atom. In the tenth O site, O(10) is bonded in an L-shaped geometry to one Mg(1) and one Cr(4) atom. In the eleventh O site, O(11) is bonded in a distorted single-bond geometry to one Cr(3) and one Pb(2) atom. In the twelfth O site, O(12) is bonded in a distorted water-like geometry to one Mg(1), one Cr(1), and one Pb(1) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(2), and one Pb(3) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Cr(4) and one Pb(4) atom. In the fifteenth O site, O(15) is bonded in a distorted single-bond geometry to one Cr(3) and one Pb(1) atom. In the sixteenth O site, O(16) is bonded in a distorted single-bond geometry to one Cr(1) and one Pb(2) atom. is represented by the CIF card [CIF]
data_MgCr4(PbO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.179
_cell_length_b   7.551
_cell_length_c   7.609
_cell_angle_alpha   90.559
_cell_angle_beta   90.139
_cell_angle_gamma   103.114
_symmetry_Int_Tables_number   1
_cell_volume   401.670
_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  0.648  0.028  0.422  1.0
  Cr  Cr1  1  0.382  0.685  0.326  1.0
  Cr  Cr2  1  0.882  0.226  0.162  1.0
  Cr  Cr3  1  0.117  0.808  0.843  1.0
  Cr  Cr4  1  0.614  0.301  0.654  1.0
  Pb  Pb5  1  0.916  0.684  0.388  1.0
  Pb  Pb6  1  0.616  0.839  0.896  1.0
  Pb  Pb7  1  0.063  0.274  0.646  1.0
  Pb  Pb8  1  0.391  0.227  0.103  1.0
  O  O9  1  0.291  0.863  0.292  1.0
  O  O10  1  0.181  0.617  0.804  1.0
  O  O11  1  0.718  0.112  0.698  1.0
  O  O12  1  0.808  0.419  0.187  1.0
  O  O13  1  0.208  0.525  0.410  1.0
  O  O14  1  0.322  0.961  0.906  1.0
  O  O15  1  0.828  0.459  0.603  1.0
  O  O16  1  0.661  0.050  0.137  1.0
  O  O17  1  0.054  0.215  0.015  1.0
  O  O18  1  0.493  0.224  0.466  1.0
  O  O19  1  0.948  0.784  0.995  1.0
  O  O20  1  0.579  0.758  0.461  1.0
  O  O21  1  0.927  0.141  0.371  1.0
  O  O22  1  0.497  0.361  0.828  1.0
  O  O23  1  0.029  0.879  0.658  1.0
  O  O24  1  0.456  0.613  0.139  1.0
[/CIF]
.
The crystal structure described by MgCr4(PbO4)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(10), one O(12), one O(13), one O(3), and one O(8) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(12), one O(16), and one O(5) atom to form CrO4 tetrahedra that share  a cornercorner with one Pb(2)O5 square pyramid. In the second Cr site, Cr(2) is bonded to one O(13), one O(4), one O(8), and one O(9) atom to form CrO4 tetrahedra that share  a cornercorner with one Pb(2)O5 square pyramid. In the third Cr site, Cr(3) is bonded to one O(11), one O(15), one O(2), and one O(6) atom to form CrO4 tetrahedra that share corners with two equivalent Pb(2)O5 square pyramids. In the fourth Cr site, Cr(4) is bonded to one O(10), one O(14), one O(3), and one O(7) atom to form CrO4 tetrahedra that share  a cornercorner with one Pb(2)O5 square pyramid. There are four inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a 6-coordinate geometry to one O(1), one O(12), one O(15), one O(4), one O(5), and one O(7) atom. In the second Pb site, Pb(2) is bonded to one O(11), one O(16), one O(3), one O(6), and one O(8) atom to form PbO5 square pyramids that share  a cornercorner with one Cr(1)O4 tetrahedra,  a cornercorner with one Cr(2)O4 tetrahedra,  a cornercorner with one Cr(4)O4 tetrahedra, and corners with two equivalent Cr(3)O4 tetrahedra. In the third Pb site, Pb(3) is bonded in a 4-coordinate geometry to one O(13), one O(3), one O(5), and one O(7) atom. In the fourth Pb site, Pb(4) is bonded in a 4-coordinate geometry to one O(14), one O(6), one O(8), and one O(9) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Cr(1) and one Pb(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Cr(3) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(4), one Pb(2), and one Pb(3) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Cr(2) and one Pb(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Cr(1), one Pb(1), and one Pb(3) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Cr(3), one Pb(2), and one Pb(4) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Cr(4), one Pb(1), and one Pb(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(2), one Pb(2), and one Pb(4) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one Cr(2) and one Pb(4) atom. In the tenth O site, O(10) is bonded in an L-shaped geometry to one Mg(1) and one Cr(4) atom. In the eleventh O site, O(11) is bonded in a distorted single-bond geometry to one Cr(3) and one Pb(2) atom. In the twelfth O site, O(12) is bonded in a distorted water-like geometry to one Mg(1), one Cr(1), and one Pb(1) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Mg(1), one Cr(2), and one Pb(3) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Cr(4) and one Pb(4) atom. In the fifteenth O site, O(15) is bonded in a distorted single-bond geometry to one Cr(3) and one Pb(1) atom. In the sixteenth O site, O(16) is bonded in a distorted single-bond geometry to one Cr(1) and one Pb(2) atom. is represented by the CIF card [CIF]
data_MgCr4(PbO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.179
_cell_length_b   7.551
_cell_length_c   7.609
_cell_angle_alpha   90.559
_cell_angle_beta   90.139
_cell_angle_gamma   103.114
_symmetry_Int_Tables_number   1
_cell_volume   401.670
_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  0.648  0.028  0.422  1.0
  Cr  Cr1  1  0.382  0.685  0.326  1.0
  Cr  Cr2  1  0.882  0.226  0.162  1.0
  Cr  Cr3  1  0.117  0.808  0.843  1.0
  Cr  Cr4  1  0.614  0.301  0.654  1.0
  Pb  Pb5  1  0.916  0.684  0.388  1.0
  Pb  Pb6  1  0.616  0.839  0.896  1.0
  Pb  Pb7  1  0.063  0.274  0.646  1.0
  Pb  Pb8  1  0.391  0.227  0.103  1.0
  O  O9  1  0.291  0.863  0.292  1.0
  O  O10  1  0.181  0.617  0.804  1.0
  O  O11  1  0.718  0.112  0.698  1.0
  O  O12  1  0.808  0.419  0.187  1.0
  O  O13  1  0.208  0.525  0.410  1.0
  O  O14  1  0.322  0.961  0.906  1.0
  O  O15  1  0.828  0.459  0.603  1.0
  O  O16  1  0.661  0.050  0.137  1.0
  O  O17  1  0.054  0.215  0.015  1.0
  O  O18  1  0.493  0.224  0.466  1.0
  O  O19  1  0.948  0.784  0.995  1.0
  O  O20  1  0.579  0.758  0.461  1.0
  O  O21  1  0.927  0.141  0.371  1.0
  O  O22  1  0.497  0.361  0.828  1.0
  O  O23  1  0.029  0.879  0.658  1.0
  O  O24  1  0.456  0.613  0.139  1.0
[/CIF]
.