The structure described by Ni2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form NiO5 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 Ni(2)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Ni(2)O6 octahedra, and edges with two equivalent Ni(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 Ni(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Ni(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 49-54°. 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 Ni(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Ni(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-51°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ni(2) and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(2) atom. In the third O site, O(7) is bonded in a bent 150 degrees geometry to one Ni(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 Ni(1), one Ni(2), and one P(2) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one Ni(1), one Ni(2), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ni2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.250
_cell_length_b   6.924
_cell_length_c   8.943
_cell_angle_alpha   66.270
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   467.671
_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
  Ni  Ni0  1  0.441  0.305  0.822  1.0
  Ni  Ni1  1  0.559  0.695  0.178  1.0
  Ni  Ni2  1  0.941  0.695  0.678  1.0
  Ni  Ni3  1  0.059  0.305  0.322  1.0
  Ni  Ni4  1  0.574  0.769  0.609  1.0
  Ni  Ni5  1  0.426  0.231  0.391  1.0
  Ni  Ni6  1  0.074  0.231  0.891  1.0
  Ni  Ni7  1  0.926  0.769  0.109  1.0
  P  P8  1  0.770  0.060  0.757  1.0
  P  P9  1  0.230  0.940  0.243  1.0
  P  P10  1  0.270  0.940  0.743  1.0
  P  P11  1  0.730  0.060  0.257  1.0
  P  P12  1  0.225  0.529  0.534  1.0
  P  P13  1  0.775  0.471  0.466  1.0
  P  P14  1  0.725  0.471  0.966  1.0
  P  P15  1  0.275  0.529  0.034  1.0
  O  O16  1  0.168  0.750  0.404  1.0
  O  O17  1  0.832  0.250  0.596  1.0
  O  O18  1  0.668  0.250  0.096  1.0
  O  O19  1  0.332  0.750  0.904  1.0
  O  O20  1  0.764  0.622  0.551  1.0
  O  O21  1  0.236  0.378  0.449  1.0
  O  O22  1  0.264  0.378  0.949  1.0
  O  O23  1  0.736  0.622  0.051  1.0
  O  O24  1  0.261  0.122  0.798  1.0
  O  O25  1  0.739  0.878  0.202  1.0
  O  O26  1  0.761  0.878  0.702  1.0
  O  O27  1  0.239  0.122  0.298  1.0
  O  O28  1  0.389  0.552  0.605  1.0
  O  O29  1  0.611  0.448  0.395  1.0
  O  O30  1  0.889  0.448  0.895  1.0
  O  O31  1  0.111  0.552  0.105  1.0
  O  O32  1  0.906  0.023  0.881  1.0
  O  O33  1  0.094  0.977  0.119  1.0
  O  O34  1  0.406  0.977  0.619  1.0
  O  O35  1  0.594  0.023  0.381  1.0
  O  O36  1  0.088  0.476  0.658  1.0
  O  O37  1  0.912  0.524  0.342  1.0
  O  O38  1  0.588  0.524  0.842  1.0
  O  O39  1  0.412  0.476  0.158  1.0
  O  O40  1  0.612  0.117  0.809  1.0
  O  O41  1  0.388  0.883  0.191  1.0
  O  O42  1  0.112  0.883  0.691  1.0
  O  O43  1  0.888  0.117  0.309  1.0
[/CIF]
.
The structure described by Ni2P2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form NiO5 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 Ni(2)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Ni(2)O6 octahedra, and edges with two equivalent Ni(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 Ni(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Ni(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 49-54°. 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 Ni(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Ni(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-51°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Ni(2) and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(2) atom. In the third O site, O(7) is bonded in a bent 150 degrees geometry to one Ni(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 Ni(1), one Ni(2), and one P(2) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one Ni(1), one Ni(2), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ni2P2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.250
_cell_length_b   6.924
_cell_length_c   8.943
_cell_angle_alpha   66.270
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   467.671
_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
  Ni  Ni0  1  0.441  0.305  0.822  1.0
  Ni  Ni1  1  0.559  0.695  0.178  1.0
  Ni  Ni2  1  0.941  0.695  0.678  1.0
  Ni  Ni3  1  0.059  0.305  0.322  1.0
  Ni  Ni4  1  0.574  0.769  0.609  1.0
  Ni  Ni5  1  0.426  0.231  0.391  1.0
  Ni  Ni6  1  0.074  0.231  0.891  1.0
  Ni  Ni7  1  0.926  0.769  0.109  1.0
  P  P8  1  0.770  0.060  0.757  1.0
  P  P9  1  0.230  0.940  0.243  1.0
  P  P10  1  0.270  0.940  0.743  1.0
  P  P11  1  0.730  0.060  0.257  1.0
  P  P12  1  0.225  0.529  0.534  1.0
  P  P13  1  0.775  0.471  0.466  1.0
  P  P14  1  0.725  0.471  0.966  1.0
  P  P15  1  0.275  0.529  0.034  1.0
  O  O16  1  0.168  0.750  0.404  1.0
  O  O17  1  0.832  0.250  0.596  1.0
  O  O18  1  0.668  0.250  0.096  1.0
  O  O19  1  0.332  0.750  0.904  1.0
  O  O20  1  0.764  0.622  0.551  1.0
  O  O21  1  0.236  0.378  0.449  1.0
  O  O22  1  0.264  0.378  0.949  1.0
  O  O23  1  0.736  0.622  0.051  1.0
  O  O24  1  0.261  0.122  0.798  1.0
  O  O25  1  0.739  0.878  0.202  1.0
  O  O26  1  0.761  0.878  0.702  1.0
  O  O27  1  0.239  0.122  0.298  1.0
  O  O28  1  0.389  0.552  0.605  1.0
  O  O29  1  0.611  0.448  0.395  1.0
  O  O30  1  0.889  0.448  0.895  1.0
  O  O31  1  0.111  0.552  0.105  1.0
  O  O32  1  0.906  0.023  0.881  1.0
  O  O33  1  0.094  0.977  0.119  1.0
  O  O34  1  0.406  0.977  0.619  1.0
  O  O35  1  0.594  0.023  0.381  1.0
  O  O36  1  0.088  0.476  0.658  1.0
  O  O37  1  0.912  0.524  0.342  1.0
  O  O38  1  0.588  0.524  0.842  1.0
  O  O39  1  0.412  0.476  0.158  1.0
  O  O40  1  0.612  0.117  0.809  1.0
  O  O41  1  0.388  0.883  0.191  1.0
  O  O42  1  0.112  0.883  0.691  1.0
  O  O43  1  0.888  0.117  0.309  1.0
[/CIF]
.