The structure described by Sn2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form distorted SnO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Sn(2)O5 square pyramids. In the second Sn site, Sn(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted SnO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Sn(1)O5 square pyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Sn(1)O5 square pyramids, corners with three equivalent Sn(2)O5 square pyramids, and  a cornercorner with one P(2)O4 tetrahedra. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Sn(1)O5 square pyramids, corners with two equivalent Sn(2)O5 square pyramids, and  a cornercorner with one P(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Sn(1), one Sn(2), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sn(1), one Sn(2), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sn(1), one Sn(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Sn(1), one Sn(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Sn(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(2) atom. is represented by the CIF card [CIF]
data_Sn2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.544
_cell_length_b   7.654
_cell_length_c   9.754
_cell_angle_alpha   66.171
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   651.768
_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
  Sn  Sn0  1  0.949  0.764  0.111  1.0
  Sn  Sn1  1  0.552  0.755  0.127  1.0
  Sn  Sn2  1  0.052  0.245  0.373  1.0
  Sn  Sn3  1  0.449  0.236  0.389  1.0
  Sn  Sn4  1  0.551  0.764  0.611  1.0
  Sn  Sn5  1  0.948  0.755  0.627  1.0
  Sn  Sn6  1  0.448  0.245  0.873  1.0
  Sn  Sn7  1  0.051  0.236  0.889  1.0
  P  P8  1  0.260  0.504  0.060  1.0
  P  P9  1  0.760  0.496  0.440  1.0
  P  P10  1  0.752  0.104  0.198  1.0
  P  P11  1  0.252  0.896  0.302  1.0
  P  P12  1  0.748  0.104  0.698  1.0
  P  P13  1  0.248  0.896  0.802  1.0
  P  P14  1  0.240  0.504  0.560  1.0
  P  P15  1  0.740  0.496  0.940  1.0
  O  O16  1  0.747  0.588  0.053  1.0
  O  O17  1  0.123  0.472  0.152  1.0
  O  O18  1  0.395  0.453  0.158  1.0
  O  O19  1  0.895  0.547  0.342  1.0
  O  O20  1  0.623  0.528  0.348  1.0
  O  O21  1  0.723  0.268  0.029  1.0
  O  O22  1  0.247  0.412  0.447  1.0
  O  O23  1  0.256  0.082  0.331  1.0
  O  O24  1  0.777  0.268  0.529  1.0
  O  O25  1  0.895  0.146  0.247  1.0
  O  O26  1  0.127  0.899  0.204  1.0
  O  O27  1  0.627  0.101  0.296  1.0
  O  O28  1  0.395  0.854  0.253  1.0
  O  O29  1  0.756  0.918  0.169  1.0
  O  O30  1  0.244  0.082  0.831  1.0
  O  O31  1  0.605  0.146  0.747  1.0
  O  O32  1  0.373  0.899  0.704  1.0
  O  O33  1  0.873  0.101  0.796  1.0
  O  O34  1  0.105  0.854  0.753  1.0
  O  O35  1  0.223  0.732  0.471  1.0
  O  O36  1  0.744  0.918  0.669  1.0
  O  O37  1  0.753  0.588  0.553  1.0
  O  O38  1  0.277  0.732  0.971  1.0
  O  O39  1  0.377  0.472  0.652  1.0
  O  O40  1  0.105  0.453  0.658  1.0
  O  O41  1  0.605  0.547  0.842  1.0
  O  O42  1  0.877  0.528  0.848  1.0
  O  O43  1  0.253  0.412  0.947  1.0
[/CIF]
.
The structure described by Sn2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form distorted SnO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Sn(2)O5 square pyramids. In the second Sn site, Sn(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted SnO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Sn(1)O5 square pyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Sn(1)O5 square pyramids, corners with three equivalent Sn(2)O5 square pyramids, and  a cornercorner with one P(2)O4 tetrahedra. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Sn(1)O5 square pyramids, corners with two equivalent Sn(2)O5 square pyramids, and  a cornercorner with one P(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Sn(1), one Sn(2), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sn(1), one Sn(2), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sn(1), one Sn(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Sn(1), one Sn(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Sn(2) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Sn(1) and one P(2) atom. is represented by the CIF card [CIF]
data_Sn2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.544
_cell_length_b   7.654
_cell_length_c   9.754
_cell_angle_alpha   66.171
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   651.768
_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
  Sn  Sn0  1  0.949  0.764  0.111  1.0
  Sn  Sn1  1  0.552  0.755  0.127  1.0
  Sn  Sn2  1  0.052  0.245  0.373  1.0
  Sn  Sn3  1  0.449  0.236  0.389  1.0
  Sn  Sn4  1  0.551  0.764  0.611  1.0
  Sn  Sn5  1  0.948  0.755  0.627  1.0
  Sn  Sn6  1  0.448  0.245  0.873  1.0
  Sn  Sn7  1  0.051  0.236  0.889  1.0
  P  P8  1  0.260  0.504  0.060  1.0
  P  P9  1  0.760  0.496  0.440  1.0
  P  P10  1  0.752  0.104  0.198  1.0
  P  P11  1  0.252  0.896  0.302  1.0
  P  P12  1  0.748  0.104  0.698  1.0
  P  P13  1  0.248  0.896  0.802  1.0
  P  P14  1  0.240  0.504  0.560  1.0
  P  P15  1  0.740  0.496  0.940  1.0
  O  O16  1  0.747  0.588  0.053  1.0
  O  O17  1  0.123  0.472  0.152  1.0
  O  O18  1  0.395  0.453  0.158  1.0
  O  O19  1  0.895  0.547  0.342  1.0
  O  O20  1  0.623  0.528  0.348  1.0
  O  O21  1  0.723  0.268  0.029  1.0
  O  O22  1  0.247  0.412  0.447  1.0
  O  O23  1  0.256  0.082  0.331  1.0
  O  O24  1  0.777  0.268  0.529  1.0
  O  O25  1  0.895  0.146  0.247  1.0
  O  O26  1  0.127  0.899  0.204  1.0
  O  O27  1  0.627  0.101  0.296  1.0
  O  O28  1  0.395  0.854  0.253  1.0
  O  O29  1  0.756  0.918  0.169  1.0
  O  O30  1  0.244  0.082  0.831  1.0
  O  O31  1  0.605  0.146  0.747  1.0
  O  O32  1  0.373  0.899  0.704  1.0
  O  O33  1  0.873  0.101  0.796  1.0
  O  O34  1  0.105  0.854  0.753  1.0
  O  O35  1  0.223  0.732  0.471  1.0
  O  O36  1  0.744  0.918  0.669  1.0
  O  O37  1  0.753  0.588  0.553  1.0
  O  O38  1  0.277  0.732  0.971  1.0
  O  O39  1  0.377  0.472  0.652  1.0
  O  O40  1  0.105  0.453  0.658  1.0
  O  O41  1  0.605  0.547  0.842  1.0
  O  O42  1  0.877  0.528  0.848  1.0
  O  O43  1  0.253  0.412  0.947  1.0
[/CIF]
.