The crystal structure described by MgNiP2O7 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Ni(1)O5 square pyramids, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. Ni(1) is bonded to one O(2), one O(4), one O(7), and two equivalent O(6) atoms to form NiO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, and  an edgeedge with one Ni(1)O5 square pyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Mg(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgNiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.242
_cell_length_b   6.539
_cell_length_c   6.944
_cell_angle_alpha   79.545
_cell_angle_beta   65.636
_cell_angle_gamma   80.337
_symmetry_Int_Tables_number   1
_cell_volume   252.555
_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
  Mg  Mg0  1  0.700  0.155  0.875  1.0
  Mg  Mg1  1  0.300  0.845  0.125  1.0
  Ni  Ni2  1  0.913  0.316  0.189  1.0
  Ni  Ni3  1  0.088  0.684  0.810  1.0
  O  O4  1  0.396  0.241  0.514  1.0
  O  O5  1  0.604  0.759  0.486  1.0
  O  O6  1  0.939  0.981  0.232  1.0
  O  O7  1  0.061  0.019  0.768  1.0
  O  O8  1  0.723  0.404  0.653  1.0
  O  O9  1  0.277  0.596  0.347  1.0
  O  O10  1  0.386  0.660  0.869  1.0
  O  O11  1  0.614  0.340  0.131  1.0
  O  O12  1  0.402  0.075  0.861  1.0
  O  O13  1  0.597  0.925  0.139  1.0
  O  O14  1  0.080  0.366  0.856  1.0
  O  O15  1  0.920  0.634  0.144  1.0
  O  O16  1  0.810  0.744  0.737  1.0
  O  O17  1  0.190  0.256  0.263  1.0
  P  P18  1  0.768  0.828  0.245  1.0
  P  P19  1  0.232  0.172  0.755  1.0
  P  P20  1  0.358  0.371  0.302  1.0
  P  P21  1  0.642  0.629  0.698  1.0
[/CIF]
.
The crystal structure described by MgNiP2O7 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Ni(1)O5 square pyramids, corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. Ni(1) is bonded to one O(2), one O(4), one O(7), and two equivalent O(6) atoms to form NiO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, and  an edgeedge with one Ni(1)O5 square pyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(2)O4 tetrahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Mg(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Ni(1) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgNiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.242
_cell_length_b   6.539
_cell_length_c   6.944
_cell_angle_alpha   79.545
_cell_angle_beta   65.636
_cell_angle_gamma   80.337
_symmetry_Int_Tables_number   1
_cell_volume   252.555
_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
  Mg  Mg0  1  0.700  0.155  0.875  1.0
  Mg  Mg1  1  0.300  0.845  0.125  1.0
  Ni  Ni2  1  0.913  0.316  0.189  1.0
  Ni  Ni3  1  0.088  0.684  0.810  1.0
  O  O4  1  0.396  0.241  0.514  1.0
  O  O5  1  0.604  0.759  0.486  1.0
  O  O6  1  0.939  0.981  0.232  1.0
  O  O7  1  0.061  0.019  0.768  1.0
  O  O8  1  0.723  0.404  0.653  1.0
  O  O9  1  0.277  0.596  0.347  1.0
  O  O10  1  0.386  0.660  0.869  1.0
  O  O11  1  0.614  0.340  0.131  1.0
  O  O12  1  0.402  0.075  0.861  1.0
  O  O13  1  0.597  0.925  0.139  1.0
  O  O14  1  0.080  0.366  0.856  1.0
  O  O15  1  0.920  0.634  0.144  1.0
  O  O16  1  0.810  0.744  0.737  1.0
  O  O17  1  0.190  0.256  0.263  1.0
  P  P18  1  0.768  0.828  0.245  1.0
  P  P19  1  0.232  0.172  0.755  1.0
  P  P20  1  0.358  0.371  0.302  1.0
  P  P21  1  0.642  0.629  0.698  1.0
[/CIF]
.