The material described by MgFeP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(10), one O(3), one O(5), one O(8), and one O(9) atom to form MgO5 trigonal bipyramids that share corners with two equivalent Fe(2)O5 square pyramids,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(10), one O(4), one O(6), one O(7), and one O(9) atom to form MgO5 trigonal bipyramids that share corners with two equivalent Fe(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(14), one O(4), one O(7), and two equivalent O(11) atoms to form FeO5 square pyramids that share  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Fe(1)O5 square pyramid. In the second Fe site, Fe(2) is bonded to one O(13), one O(3), one O(8), and two equivalent O(12) atoms to form FeO5 square pyramids that share  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, and  an edgeedge with one Fe(2)O5 square pyramid. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(10), one O(12), one O(2), and one O(3) atom to form PO4 tetrahedra that share corners with three equivalent Fe(2)O5 square pyramids,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one Mg(2)O5 trigonal bipyramid, and corners with two equivalent Mg(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(11), one O(4), and one O(9) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O5 square pyramids,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and corners with two equivalent Mg(2)O5 trigonal bipyramids. In the third P site, P(3) is bonded to one O(1), one O(14), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Fe(2)O5 square pyramid,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  a cornercorner with one Mg(2)O5 trigonal bipyramid. In the fourth P site, P(4) is bonded to one O(13), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Fe(2)O5 square pyramid,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  a cornercorner with one Mg(2)O5 trigonal bipyramid. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one P(2) and one P(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one P(1) and one P(4) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(2), one Fe(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(1) and one P(4) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(2) and one P(3) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Mg(2), one Fe(1), and one P(4) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Mg(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(2) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to two equivalent Fe(2) and one P(1) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(4) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. is represented by the CIF card [CIF]
data_MgFeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.219
_cell_length_b   6.790
_cell_length_c   7.122
_cell_angle_alpha   77.235
_cell_angle_beta   65.090
_cell_angle_gamma   80.022
_symmetry_Int_Tables_number   1
_cell_volume   264.914
_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
  Fe  Fe0  1  0.912  0.307  0.195  1.0
  Fe  Fe1  1  0.088  0.693  0.805  1.0
  Mg  Mg2  1  0.692  0.164  0.885  1.0
  Mg  Mg3  1  0.308  0.836  0.115  1.0
  O  O4  1  0.400  0.247  0.516  1.0
  O  O5  1  0.600  0.753  0.484  1.0
  O  O6  1  0.948  0.960  0.225  1.0
  O  O7  1  0.052  0.040  0.775  1.0
  O  O8  1  0.713  0.414  0.671  1.0
  O  O9  1  0.287  0.586  0.329  1.0
  O  O10  1  0.389  0.673  0.866  1.0
  O  O11  1  0.611  0.327  0.134  1.0
  O  O12  1  0.403  0.077  0.861  1.0
  O  O13  1  0.597  0.923  0.139  1.0
  O  O14  1  0.094  0.370  0.853  1.0
  O  O15  1  0.906  0.630  0.147  1.0
  O  O16  1  0.820  0.748  0.716  1.0
  O  O17  1  0.180  0.252  0.284  1.0
  P  P18  1  0.769  0.819  0.242  1.0
  P  P19  1  0.231  0.181  0.758  1.0
  P  P20  1  0.357  0.365  0.306  1.0
  P  P21  1  0.643  0.635  0.694  1.0
[/CIF]
.
The material described by MgFeP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(10), one O(3), one O(5), one O(8), and one O(9) atom to form MgO5 trigonal bipyramids that share corners with two equivalent Fe(2)O5 square pyramids,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(10), one O(4), one O(6), one O(7), and one O(9) atom to form MgO5 trigonal bipyramids that share corners with two equivalent Fe(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(14), one O(4), one O(7), and two equivalent O(11) atoms to form FeO5 square pyramids that share  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Fe(1)O5 square pyramid. In the second Fe site, Fe(2) is bonded to one O(13), one O(3), one O(8), and two equivalent O(12) atoms to form FeO5 square pyramids that share  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, and  an edgeedge with one Fe(2)O5 square pyramid. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(10), one O(12), one O(2), and one O(3) atom to form PO4 tetrahedra that share corners with three equivalent Fe(2)O5 square pyramids,  a cornercorner with one P(4)O4 tetrahedra,  a cornercorner with one Mg(2)O5 trigonal bipyramid, and corners with two equivalent Mg(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(11), one O(4), and one O(9) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O5 square pyramids,  a cornercorner with one P(3)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and corners with two equivalent Mg(2)O5 trigonal bipyramids. In the third P site, P(3) is bonded to one O(1), one O(14), one O(6), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Fe(2)O5 square pyramid,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  a cornercorner with one Mg(2)O5 trigonal bipyramid. In the fourth P site, P(4) is bonded to one O(13), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O5 square pyramid,  a cornercorner with one Fe(2)O5 square pyramid,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, and  a cornercorner with one Mg(2)O5 trigonal bipyramid. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one P(2) and one P(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one P(1) and one P(4) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(2), one Fe(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(1) and one P(4) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(2) and one P(3) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Mg(2), one Fe(1), and one P(4) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Mg(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(2) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to two equivalent Fe(2) and one P(1) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(4) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. is represented by the CIF card [CIF]
data_MgFeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.219
_cell_length_b   6.790
_cell_length_c   7.122
_cell_angle_alpha   77.235
_cell_angle_beta   65.090
_cell_angle_gamma   80.022
_symmetry_Int_Tables_number   1
_cell_volume   264.914
_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
  Fe  Fe0  1  0.912  0.307  0.195  1.0
  Fe  Fe1  1  0.088  0.693  0.805  1.0
  Mg  Mg2  1  0.692  0.164  0.885  1.0
  Mg  Mg3  1  0.308  0.836  0.115  1.0
  O  O4  1  0.400  0.247  0.516  1.0
  O  O5  1  0.600  0.753  0.484  1.0
  O  O6  1  0.948  0.960  0.225  1.0
  O  O7  1  0.052  0.040  0.775  1.0
  O  O8  1  0.713  0.414  0.671  1.0
  O  O9  1  0.287  0.586  0.329  1.0
  O  O10  1  0.389  0.673  0.866  1.0
  O  O11  1  0.611  0.327  0.134  1.0
  O  O12  1  0.403  0.077  0.861  1.0
  O  O13  1  0.597  0.923  0.139  1.0
  O  O14  1  0.094  0.370  0.853  1.0
  O  O15  1  0.906  0.630  0.147  1.0
  O  O16  1  0.820  0.748  0.716  1.0
  O  O17  1  0.180  0.252  0.284  1.0
  P  P18  1  0.769  0.819  0.242  1.0
  P  P19  1  0.231  0.181  0.758  1.0
  P  P20  1  0.357  0.365  0.306  1.0
  P  P21  1  0.643  0.635  0.694  1.0
[/CIF]
.