The compound described by Mg2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Mg(2)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 48-52°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 35-51°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2) and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(2) atom. In the third O site, O(7) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(2) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(1) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.278
_cell_length_b   6.941
_cell_length_c   9.049
_cell_angle_alpha   66.145
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   475.525
_cell_formula_units_Z   4
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  0.439  0.301  0.826  1.0
  Mg  Mg1  1  0.561  0.699  0.174  1.0
  Mg  Mg2  1  0.939  0.699  0.674  1.0
  Mg  Mg3  1  0.061  0.301  0.326  1.0
  Mg  Mg4  1  0.569  0.767  0.610  1.0
  Mg  Mg5  1  0.431  0.233  0.390  1.0
  Mg  Mg6  1  0.069  0.233  0.890  1.0
  Mg  Mg7  1  0.931  0.767  0.110  1.0
  P  P8  1  0.767  0.057  0.760  1.0
  P  P9  1  0.233  0.943  0.240  1.0
  P  P10  1  0.267  0.943  0.740  1.0
  P  P11  1  0.733  0.057  0.260  1.0
  P  P12  1  0.226  0.530  0.534  1.0
  P  P13  1  0.774  0.470  0.466  1.0
  P  P14  1  0.726  0.470  0.966  1.0
  P  P15  1  0.274  0.530  0.034  1.0
  O  O16  1  0.172  0.749  0.400  1.0
  O  O17  1  0.828  0.251  0.600  1.0
  O  O18  1  0.672  0.251  0.100  1.0
  O  O19  1  0.328  0.749  0.900  1.0
  O  O20  1  0.763  0.625  0.546  1.0
  O  O21  1  0.237  0.375  0.454  1.0
  O  O22  1  0.263  0.375  0.954  1.0
  O  O23  1  0.737  0.625  0.046  1.0
  O  O24  1  0.258  0.121  0.797  1.0
  O  O25  1  0.742  0.879  0.203  1.0
  O  O26  1  0.758  0.879  0.703  1.0
  O  O27  1  0.242  0.121  0.297  1.0
  O  O28  1  0.388  0.552  0.605  1.0
  O  O29  1  0.612  0.448  0.395  1.0
  O  O30  1  0.888  0.448  0.895  1.0
  O  O31  1  0.112  0.552  0.105  1.0
  O  O32  1  0.903  0.022  0.881  1.0
  O  O33  1  0.097  0.978  0.119  1.0
  O  O34  1  0.403  0.978  0.619  1.0
  O  O35  1  0.597  0.022  0.381  1.0
  O  O36  1  0.090  0.482  0.656  1.0
  O  O37  1  0.910  0.518  0.344  1.0
  O  O38  1  0.590  0.518  0.844  1.0
  O  O39  1  0.410  0.482  0.156  1.0
  O  O40  1  0.610  0.113  0.813  1.0
  O  O41  1  0.390  0.887  0.187  1.0
  O  O42  1  0.110  0.887  0.687  1.0
  O  O43  1  0.890  0.113  0.313  1.0
[/CIF]
.
The compound described by Mg2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Mg(2)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 48-52°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 35-51°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2) and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(2) atom. In the third O site, O(7) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the fourth O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(2) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one P(1) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.278
_cell_length_b   6.941
_cell_length_c   9.049
_cell_angle_alpha   66.145
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   475.525
_cell_formula_units_Z   4
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  0.439  0.301  0.826  1.0
  Mg  Mg1  1  0.561  0.699  0.174  1.0
  Mg  Mg2  1  0.939  0.699  0.674  1.0
  Mg  Mg3  1  0.061  0.301  0.326  1.0
  Mg  Mg4  1  0.569  0.767  0.610  1.0
  Mg  Mg5  1  0.431  0.233  0.390  1.0
  Mg  Mg6  1  0.069  0.233  0.890  1.0
  Mg  Mg7  1  0.931  0.767  0.110  1.0
  P  P8  1  0.767  0.057  0.760  1.0
  P  P9  1  0.233  0.943  0.240  1.0
  P  P10  1  0.267  0.943  0.740  1.0
  P  P11  1  0.733  0.057  0.260  1.0
  P  P12  1  0.226  0.530  0.534  1.0
  P  P13  1  0.774  0.470  0.466  1.0
  P  P14  1  0.726  0.470  0.966  1.0
  P  P15  1  0.274  0.530  0.034  1.0
  O  O16  1  0.172  0.749  0.400  1.0
  O  O17  1  0.828  0.251  0.600  1.0
  O  O18  1  0.672  0.251  0.100  1.0
  O  O19  1  0.328  0.749  0.900  1.0
  O  O20  1  0.763  0.625  0.546  1.0
  O  O21  1  0.237  0.375  0.454  1.0
  O  O22  1  0.263  0.375  0.954  1.0
  O  O23  1  0.737  0.625  0.046  1.0
  O  O24  1  0.258  0.121  0.797  1.0
  O  O25  1  0.742  0.879  0.203  1.0
  O  O26  1  0.758  0.879  0.703  1.0
  O  O27  1  0.242  0.121  0.297  1.0
  O  O28  1  0.388  0.552  0.605  1.0
  O  O29  1  0.612  0.448  0.395  1.0
  O  O30  1  0.888  0.448  0.895  1.0
  O  O31  1  0.112  0.552  0.105  1.0
  O  O32  1  0.903  0.022  0.881  1.0
  O  O33  1  0.097  0.978  0.119  1.0
  O  O34  1  0.403  0.978  0.619  1.0
  O  O35  1  0.597  0.022  0.381  1.0
  O  O36  1  0.090  0.482  0.656  1.0
  O  O37  1  0.910  0.518  0.344  1.0
  O  O38  1  0.590  0.518  0.844  1.0
  O  O39  1  0.410  0.482  0.156  1.0
  O  O40  1  0.610  0.113  0.813  1.0
  O  O41  1  0.390  0.887  0.187  1.0
  O  O42  1  0.110  0.887  0.687  1.0
  O  O43  1  0.890  0.113  0.313  1.0
[/CIF]
.