The material described by Sr8MgP4(O4I)4 crystallizes in the triclinic P1 space group. There are eight inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(13), one O(15), one O(5), one I(3), and one I(4) atom. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one Mg(1), one O(16), one O(2), one O(7), one I(1), one I(3), and one I(4) atom. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one O(12), one O(13), one O(15), one O(2), one O(3), one O(6), one O(7), and one I(1) atom. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(14), one O(16), one O(4), one O(5), one O(8), and one I(2) atom. In the fifth Sr site, Sr(5) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(16), one O(2), one O(8), one I(2), one I(3), and one I(4) atom. In the sixth Sr site, Sr(6) is bonded in a 8-coordinate geometry to one O(1), one O(12), one O(15), one O(7), one O(9), one I(1), one I(3), and one I(4) atom. In the seventh Sr site, Sr(7) is bonded in a 8-coordinate geometry to one O(12), one O(14), one O(4), one O(6), one O(9), one I(1), one I(2), and one I(4) atom. In the eighth Sr site, Sr(8) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(13), one O(3), one O(5), one I(1), one I(2), and one I(3) atom. Mg(1) is bonded in a 3-coordinate geometry to one Sr(2), one O(14), one O(3), and one O(6) atom. There are four inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one O(1), one O(10), one O(16), and one O(7) atom. In the second P site, P(2) is bonded in a tetrahedral geometry to one O(15), one O(2), one O(8), and one O(9) atom. In the third P site, P(3) is bonded in a tetrahedral geometry to one O(12), one O(14), one O(3), and one O(5) atom. In the fourth P site, P(4) is bonded in a tetrahedral geometry to one O(11), one O(13), one O(4), and one O(6) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(4), one Sr(6), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Sr(2), one Sr(3), one Sr(5), and one P(2) atom. In the third O site, O(3) is bonded to one Sr(3), one Sr(8), one Mg(1), and one P(3) atom to form distorted OSr2MgP tetrahedra that share  a cornercorner with one I(3)Sr5 trigonal bipyramid. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(4), one Sr(7), and one P(4) atom. In the fifth O site, O(5) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(4), one Sr(8), and one P(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Sr(3), one Sr(7), one Mg(1), and one P(4) atom. In the seventh O site, O(7) is bonded in a 1-coordinate geometry to one Sr(2), one Sr(3), one Sr(6), and one P(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Sr(4), one Sr(5), and one P(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Sr(6), one Sr(7), and one P(2) atom. In the tenth O site, O(10) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(5), one Sr(8), and one P(1) atom. In the eleventh O site, O(11) is bonded in a distorted single-bond geometry to one Sr(4), one Sr(5), one Sr(8), and one P(4) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one Sr(3), one Sr(6), one Sr(7), and one P(3) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(3), one Sr(8), and one P(4) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Sr(4), one Sr(7), one Mg(1), and one P(3) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(3), one Sr(6), and one P(2) atom. In the sixteenth O site, O(16) is bonded in a distorted single-bond geometry to one Sr(2), one Sr(4), one Sr(5), and one P(1) atom. There are four inequivalent I sites. In the first I site, I(1) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), one Sr(6), one Sr(7), and one Sr(8) atom. In the second I site, I(2) is bonded in a 4-coordinate geometry to one Sr(4), one Sr(5), one Sr(7), and one Sr(8) atom. In the third I site, I(3) is bonded to one Sr(1), one Sr(2), one Sr(5), one Sr(6), and one Sr(8) atom to form ISr5 trigonal bipyramids that share  a cornercorner with one O(3)Sr2MgP tetrahedra and edges with two equivalent I(4)Sr5 trigonal bipyramids. In the fourth I site, I(4) is bonded to one Sr(1), one Sr(2), one Sr(5), one Sr(6), and one Sr(7) atom to form distorted edge-sharing ISr5 trigonal bipyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sr8MgP4(IO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.192
_cell_length_b   8.904
_cell_length_c   9.795
_cell_angle_alpha   89.081
_cell_angle_beta   116.210
_cell_angle_gamma   91.290
_symmetry_Int_Tables_number   1
_cell_volume   719.083
_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
  Sr  Sr0  1  0.963  0.803  0.844  1.0
  Sr  Sr1  1  0.473  0.346  0.294  1.0
  Sr  Sr2  1  0.040  0.179  0.115  1.0
  Sr  Sr3  1  0.461  0.681  0.878  1.0
  Sr  Sr4  1  0.484  0.850  0.241  1.0
  Sr  Sr5  1  0.042  0.326  0.746  1.0
  Sr  Sr6  1  0.513  0.160  0.759  1.0
  Sr  Sr7  1  0.964  0.666  0.225  1.0
  Mg  Mg8  1  0.701  0.302  0.143  1.0
  P  P9  1  0.231  0.561  0.040  1.0
  P  P10  1  0.267  0.063  0.962  1.0
  P  P11  1  0.771  0.449  0.921  1.0
  P  P12  1  0.739  0.938  0.027  1.0
  I  I13  1  0.220  0.365  0.481  1.0
  I  I14  1  0.274  0.866  0.489  1.0
  I  I15  1  0.793  0.617  0.500  1.0
  I  I16  1  0.714  0.079  0.540  1.0
  O  O17  1  0.171  0.580  0.864  1.0
  O  O18  1  0.337  0.098  0.138  1.0
  O  O19  1  0.877  0.415  0.097  1.0
  O  O20  1  0.623  0.906  0.858  1.0
  O  O21  1  0.784  0.619  0.895  1.0
  O  O22  1  0.732  0.111  0.049  1.0
  O  O23  1  0.198  0.396  0.073  1.0
  O  O24  1  0.313  0.898  0.949  1.0
  O  O25  1  0.319  0.176  0.870  1.0
  O  O26  1  0.147  0.675  0.098  1.0
  O  O27  1  0.688  0.834  0.129  1.0
  O  O28  1  0.825  0.342  0.831  1.0
  O  O29  1  0.919  0.906  0.068  1.0
  O  O30  1  0.591  0.411  0.890  1.0
  O  O31  1  0.077  0.075  0.895  1.0
  O  O32  1  0.419  0.592  0.124  1.0
[/CIF]
.
The material described by Sr8MgP4(O4I)4 crystallizes in the triclinic P1 space group. There are eight inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(13), one O(15), one O(5), one I(3), and one I(4) atom. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one Mg(1), one O(16), one O(2), one O(7), one I(1), one I(3), and one I(4) atom. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one O(12), one O(13), one O(15), one O(2), one O(3), one O(6), one O(7), and one I(1) atom. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(14), one O(16), one O(4), one O(5), one O(8), and one I(2) atom. In the fifth Sr site, Sr(5) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(16), one O(2), one O(8), one I(2), one I(3), and one I(4) atom. In the sixth Sr site, Sr(6) is bonded in a 8-coordinate geometry to one O(1), one O(12), one O(15), one O(7), one O(9), one I(1), one I(3), and one I(4) atom. In the seventh Sr site, Sr(7) is bonded in a 8-coordinate geometry to one O(12), one O(14), one O(4), one O(6), one O(9), one I(1), one I(2), and one I(4) atom. In the eighth Sr site, Sr(8) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(13), one O(3), one O(5), one I(1), one I(2), and one I(3) atom. Mg(1) is bonded in a 3-coordinate geometry to one Sr(2), one O(14), one O(3), and one O(6) atom. There are four inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one O(1), one O(10), one O(16), and one O(7) atom. In the second P site, P(2) is bonded in a tetrahedral geometry to one O(15), one O(2), one O(8), and one O(9) atom. In the third P site, P(3) is bonded in a tetrahedral geometry to one O(12), one O(14), one O(3), and one O(5) atom. In the fourth P site, P(4) is bonded in a tetrahedral geometry to one O(11), one O(13), one O(4), and one O(6) atom. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(4), one Sr(6), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Sr(2), one Sr(3), one Sr(5), and one P(2) atom. In the third O site, O(3) is bonded to one Sr(3), one Sr(8), one Mg(1), and one P(3) atom to form distorted OSr2MgP tetrahedra that share  a cornercorner with one I(3)Sr5 trigonal bipyramid. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(4), one Sr(7), and one P(4) atom. In the fifth O site, O(5) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(4), one Sr(8), and one P(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Sr(3), one Sr(7), one Mg(1), and one P(4) atom. In the seventh O site, O(7) is bonded in a 1-coordinate geometry to one Sr(2), one Sr(3), one Sr(6), and one P(1) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Sr(4), one Sr(5), and one P(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Sr(6), one Sr(7), and one P(2) atom. In the tenth O site, O(10) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(5), one Sr(8), and one P(1) atom. In the eleventh O site, O(11) is bonded in a distorted single-bond geometry to one Sr(4), one Sr(5), one Sr(8), and one P(4) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one Sr(3), one Sr(6), one Sr(7), and one P(3) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(3), one Sr(8), and one P(4) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Sr(4), one Sr(7), one Mg(1), and one P(3) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(3), one Sr(6), and one P(2) atom. In the sixteenth O site, O(16) is bonded in a distorted single-bond geometry to one Sr(2), one Sr(4), one Sr(5), and one P(1) atom. There are four inequivalent I sites. In the first I site, I(1) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), one Sr(6), one Sr(7), and one Sr(8) atom. In the second I site, I(2) is bonded in a 4-coordinate geometry to one Sr(4), one Sr(5), one Sr(7), and one Sr(8) atom. In the third I site, I(3) is bonded to one Sr(1), one Sr(2), one Sr(5), one Sr(6), and one Sr(8) atom to form ISr5 trigonal bipyramids that share  a cornercorner with one O(3)Sr2MgP tetrahedra and edges with two equivalent I(4)Sr5 trigonal bipyramids. In the fourth I site, I(4) is bonded to one Sr(1), one Sr(2), one Sr(5), one Sr(6), and one Sr(7) atom to form distorted edge-sharing ISr5 trigonal bipyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sr8MgP4(IO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.192
_cell_length_b   8.904
_cell_length_c   9.795
_cell_angle_alpha   89.081
_cell_angle_beta   116.210
_cell_angle_gamma   91.290
_symmetry_Int_Tables_number   1
_cell_volume   719.083
_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
  Sr  Sr0  1  0.963  0.803  0.844  1.0
  Sr  Sr1  1  0.473  0.346  0.294  1.0
  Sr  Sr2  1  0.040  0.179  0.115  1.0
  Sr  Sr3  1  0.461  0.681  0.878  1.0
  Sr  Sr4  1  0.484  0.850  0.241  1.0
  Sr  Sr5  1  0.042  0.326  0.746  1.0
  Sr  Sr6  1  0.513  0.160  0.759  1.0
  Sr  Sr7  1  0.964  0.666  0.225  1.0
  Mg  Mg8  1  0.701  0.302  0.143  1.0
  P  P9  1  0.231  0.561  0.040  1.0
  P  P10  1  0.267  0.063  0.962  1.0
  P  P11  1  0.771  0.449  0.921  1.0
  P  P12  1  0.739  0.938  0.027  1.0
  I  I13  1  0.220  0.365  0.481  1.0
  I  I14  1  0.274  0.866  0.489  1.0
  I  I15  1  0.793  0.617  0.500  1.0
  I  I16  1  0.714  0.079  0.540  1.0
  O  O17  1  0.171  0.580  0.864  1.0
  O  O18  1  0.337  0.098  0.138  1.0
  O  O19  1  0.877  0.415  0.097  1.0
  O  O20  1  0.623  0.906  0.858  1.0
  O  O21  1  0.784  0.619  0.895  1.0
  O  O22  1  0.732  0.111  0.049  1.0
  O  O23  1  0.198  0.396  0.073  1.0
  O  O24  1  0.313  0.898  0.949  1.0
  O  O25  1  0.319  0.176  0.870  1.0
  O  O26  1  0.147  0.675  0.098  1.0
  O  O27  1  0.688  0.834  0.129  1.0
  O  O28  1  0.825  0.342  0.831  1.0
  O  O29  1  0.919  0.906  0.068  1.0
  O  O30  1  0.591  0.411  0.890  1.0
  O  O31  1  0.077  0.075  0.895  1.0
  O  O32  1  0.419  0.592  0.124  1.0
[/CIF]
.