The material structure described by MgFe2P2(HO)18 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(9) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra and corners with four equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the second Fe site, Fe(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. P(1) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, and corners with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-50°. There are nine inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(3) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) and one O(9) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(1) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(1) atom. In the seventh H site, H(7) is bonded in a distorted single-bond geometry to one O(3) and one O(4) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(4) and one O(6) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(5) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one Mg(1), one H(5), and one H(6) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one H(3), and one H(4) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one H(1), one H(2), and one H(7) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Fe(2), one H(7), and one H(8) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Fe(1), one Fe(2), and one H(9) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Fe(1), one P(1), and one H(8) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Mg(1) and one P(1) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Fe(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1), one P(1), and one H(4) atom. is represented by the CIF file [CIF]
data_MgFe2P2(HO)18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.396
_cell_length_b   7.277
_cell_length_c   10.336
_cell_angle_alpha   97.663
_cell_angle_beta   101.335
_cell_angle_gamma   111.052
_symmetry_Int_Tables_number   1
_cell_volume   362.093
_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  0.000  0.000  0.000  1.0
  Fe  Fe1  1  0.500  0.000  0.500  1.0
  Fe  Fe2  1  0.500  0.500  0.500  1.0
  P  P3  1  0.981  0.073  0.327  1.0
  P  P4  1  0.019  0.927  0.673  1.0
  H  H5  1  0.904  0.426  0.734  1.0
  H  H6  1  0.096  0.574  0.266  1.0
  H  H7  1  0.077  0.649  0.817  1.0
  H  H8  1  0.923  0.351  0.183  1.0
  H  H9  1  0.538  0.013  0.121  1.0
  H  H10  1  0.686  0.039  0.796  1.0
  H  H11  1  0.165  0.386  0.945  1.0
  H  H12  1  0.835  0.614  0.055  1.0
  H  H13  1  0.322  0.402  0.095  1.0
  H  H14  1  0.678  0.598  0.905  1.0
  H  H15  1  0.692  0.513  0.268  1.0
  H  H16  1  0.308  0.487  0.732  1.0
  H  H17  1  0.610  0.696  0.316  1.0
  H  H18  1  0.390  0.304  0.684  1.0
  H  H19  1  0.844  0.324  0.482  1.0
  H  H20  1  0.156  0.676  0.518  1.0
  H  H21  1  0.462  0.987  0.879  1.0
  H  H22  1  0.314  0.961  0.204  1.0
  O  O23  1  0.234  0.310  0.005  1.0
  O  O24  1  0.662  0.030  0.888  1.0
  O  O25  1  0.338  0.970  0.112  1.0
  O  O26  1  0.927  0.491  0.195  1.0
  O  O27  1  0.073  0.509  0.805  1.0
  O  O28  1  0.455  0.455  0.698  1.0
  O  O29  1  0.668  0.298  0.508  1.0
  O  O30  1  0.332  0.702  0.492  1.0
  O  O31  1  0.712  0.948  0.364  1.0
  O  O32  1  0.288  0.052  0.636  1.0
  O  O33  1  0.095  0.905  0.821  1.0
  O  O34  1  0.905  0.095  0.179  1.0
  O  O35  1  0.884  0.714  0.576  1.0
  O  O36  1  0.116  0.286  0.424  1.0
  O  O37  1  0.821  0.038  0.659  1.0
  O  O38  1  0.179  0.962  0.341  1.0
  O  O39  1  0.766  0.690  0.995  1.0
  O  O40  1  0.545  0.545  0.302  1.0
[/CIF]
.
The material structure described by MgFe2P2(HO)18 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms to form MgO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(9) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra and corners with four equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the second Fe site, Fe(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. P(1) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, and corners with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-50°. There are nine inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(3) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) and one O(9) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(1) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(1) atom. In the seventh H site, H(7) is bonded in a distorted single-bond geometry to one O(3) and one O(4) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(4) and one O(6) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(5) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one Mg(1), one H(5), and one H(6) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one H(3), and one H(4) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one H(1), one H(2), and one H(7) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Fe(2), one H(7), and one H(8) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Fe(1), one Fe(2), and one H(9) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Fe(1), one P(1), and one H(8) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Mg(1) and one P(1) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Fe(2) and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1), one P(1), and one H(4) atom. is represented by the CIF file [CIF]
data_MgFe2P2(HO)18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.396
_cell_length_b   7.277
_cell_length_c   10.336
_cell_angle_alpha   97.663
_cell_angle_beta   101.335
_cell_angle_gamma   111.052
_symmetry_Int_Tables_number   1
_cell_volume   362.093
_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  0.000  0.000  0.000  1.0
  Fe  Fe1  1  0.500  0.000  0.500  1.0
  Fe  Fe2  1  0.500  0.500  0.500  1.0
  P  P3  1  0.981  0.073  0.327  1.0
  P  P4  1  0.019  0.927  0.673  1.0
  H  H5  1  0.904  0.426  0.734  1.0
  H  H6  1  0.096  0.574  0.266  1.0
  H  H7  1  0.077  0.649  0.817  1.0
  H  H8  1  0.923  0.351  0.183  1.0
  H  H9  1  0.538  0.013  0.121  1.0
  H  H10  1  0.686  0.039  0.796  1.0
  H  H11  1  0.165  0.386  0.945  1.0
  H  H12  1  0.835  0.614  0.055  1.0
  H  H13  1  0.322  0.402  0.095  1.0
  H  H14  1  0.678  0.598  0.905  1.0
  H  H15  1  0.692  0.513  0.268  1.0
  H  H16  1  0.308  0.487  0.732  1.0
  H  H17  1  0.610  0.696  0.316  1.0
  H  H18  1  0.390  0.304  0.684  1.0
  H  H19  1  0.844  0.324  0.482  1.0
  H  H20  1  0.156  0.676  0.518  1.0
  H  H21  1  0.462  0.987  0.879  1.0
  H  H22  1  0.314  0.961  0.204  1.0
  O  O23  1  0.234  0.310  0.005  1.0
  O  O24  1  0.662  0.030  0.888  1.0
  O  O25  1  0.338  0.970  0.112  1.0
  O  O26  1  0.927  0.491  0.195  1.0
  O  O27  1  0.073  0.509  0.805  1.0
  O  O28  1  0.455  0.455  0.698  1.0
  O  O29  1  0.668  0.298  0.508  1.0
  O  O30  1  0.332  0.702  0.492  1.0
  O  O31  1  0.712  0.948  0.364  1.0
  O  O32  1  0.288  0.052  0.636  1.0
  O  O33  1  0.095  0.905  0.821  1.0
  O  O34  1  0.905  0.095  0.179  1.0
  O  O35  1  0.884  0.714  0.576  1.0
  O  O36  1  0.116  0.286  0.424  1.0
  O  O37  1  0.821  0.038  0.659  1.0
  O  O38  1  0.179  0.962  0.341  1.0
  O  O39  1  0.766  0.690  0.995  1.0
  O  O40  1  0.545  0.545  0.302  1.0
[/CIF]
.