The compound described by CaNi3O7 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CaO7 pentagonal bipyramids that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, corners with six equivalent Ni(1)O5 trigonal bipyramids, edges with two equivalent Ni(1)O5 trigonal bipyramids, and edges with two equivalent Ni(2)O5 trigonal bipyramids. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted NiO5 trigonal bipyramids that share corners with three equivalent Ca(1)O7 pentagonal bipyramids, corners with two equivalent Ni(2)O5 trigonal bipyramids,  an edgeedge with one Ca(1)O7 pentagonal bipyramid,  an edgeedge with one Ni(2)O5 trigonal bipyramid, and edges with two equivalent Ni(1)O5 trigonal bipyramids. In the second Ni site, Ni(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one Ca(1)O7 pentagonal bipyramid, corners with four equivalent Ni(1)O5 trigonal bipyramids, edges with two equivalent Ca(1)O7 pentagonal bipyramids, and edges with two equivalent Ni(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one Ni(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Ca(1) and one Ni(1) atom. In the third O site, O(1) is bonded to one Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing OCaNi3 trigonal pyramids. In the fourth O site, O(2) is bonded in a distorted see-saw-like geometry to one Ca(1), one Ni(2), and two equivalent Ni(1) atoms. is represented by the CIF card [CIF]
data_CaNi3O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.266
_cell_length_b   10.249
_cell_length_c   11.423
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   616.467
_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
  Ca  Ca0  1  0.674  0.750  0.086  1.0
  Ca  Ca1  1  0.174  0.250  0.414  1.0
  Ca  Ca2  1  0.326  0.250  0.914  1.0
  Ca  Ca3  1  0.826  0.750  0.586  1.0
  Ni  Ni4  1  0.300  0.024  0.700  1.0
  Ni  Ni5  1  0.800  0.976  0.800  1.0
  Ni  Ni6  1  0.700  0.524  0.300  1.0
  Ni  Ni7  1  0.200  0.476  0.200  1.0
  Ni  Ni8  1  0.324  0.750  0.762  1.0
  Ni  Ni9  1  0.824  0.250  0.738  1.0
  Ni  Ni10  1  0.676  0.250  0.238  1.0
  Ni  Ni11  1  0.176  0.750  0.262  1.0
  Ni  Ni12  1  0.800  0.524  0.800  1.0
  Ni  Ni13  1  0.300  0.476  0.700  1.0
  Ni  Ni14  1  0.200  0.024  0.200  1.0
  Ni  Ni15  1  0.700  0.976  0.300  1.0
  O  O16  1  0.928  0.121  0.273  1.0
  O  O17  1  0.428  0.879  0.227  1.0
  O  O18  1  0.072  0.621  0.727  1.0
  O  O19  1  0.572  0.379  0.773  1.0
  O  O20  1  0.072  0.879  0.727  1.0
  O  O21  1  0.572  0.121  0.773  1.0
  O  O22  1  0.928  0.379  0.273  1.0
  O  O23  1  0.428  0.621  0.227  1.0
  O  O24  1  0.452  0.120  0.294  1.0
  O  O25  1  0.952  0.880  0.206  1.0
  O  O26  1  0.548  0.620  0.706  1.0
  O  O27  1  0.048  0.380  0.794  1.0
  O  O28  1  0.548  0.880  0.706  1.0
  O  O29  1  0.048  0.120  0.794  1.0
  O  O30  1  0.452  0.380  0.294  1.0
  O  O31  1  0.952  0.620  0.206  1.0
  O  O32  1  0.089  0.750  0.424  1.0
  O  O33  1  0.589  0.250  0.076  1.0
  O  O34  1  0.911  0.250  0.576  1.0
  O  O35  1  0.411  0.750  0.924  1.0
  O  O36  1  0.259  0.406  0.059  1.0
  O  O37  1  0.759  0.594  0.441  1.0
  O  O38  1  0.741  0.906  0.941  1.0
  O  O39  1  0.241  0.094  0.559  1.0
  O  O40  1  0.741  0.594  0.941  1.0
  O  O41  1  0.241  0.406  0.559  1.0
  O  O42  1  0.259  0.094  0.059  1.0
  O  O43  1  0.759  0.906  0.441  1.0
[/CIF]
.
The compound described by CaNi3O7 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CaO7 pentagonal bipyramids that share  a cornercorner with one Ni(2)O5 trigonal bipyramid, corners with six equivalent Ni(1)O5 trigonal bipyramids, edges with two equivalent Ni(1)O5 trigonal bipyramids, and edges with two equivalent Ni(2)O5 trigonal bipyramids. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted NiO5 trigonal bipyramids that share corners with three equivalent Ca(1)O7 pentagonal bipyramids, corners with two equivalent Ni(2)O5 trigonal bipyramids,  an edgeedge with one Ca(1)O7 pentagonal bipyramid,  an edgeedge with one Ni(2)O5 trigonal bipyramid, and edges with two equivalent Ni(1)O5 trigonal bipyramids. In the second Ni site, Ni(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NiO5 trigonal bipyramids that share  a cornercorner with one Ca(1)O7 pentagonal bipyramid, corners with four equivalent Ni(1)O5 trigonal bipyramids, edges with two equivalent Ca(1)O7 pentagonal bipyramids, and edges with two equivalent Ni(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one Ni(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Ca(1) and one Ni(1) atom. In the third O site, O(1) is bonded to one Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing OCaNi3 trigonal pyramids. In the fourth O site, O(2) is bonded in a distorted see-saw-like geometry to one Ca(1), one Ni(2), and two equivalent Ni(1) atoms. is represented by the CIF card [CIF]
data_CaNi3O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.266
_cell_length_b   10.249
_cell_length_c   11.423
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   616.467
_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
  Ca  Ca0  1  0.674  0.750  0.086  1.0
  Ca  Ca1  1  0.174  0.250  0.414  1.0
  Ca  Ca2  1  0.326  0.250  0.914  1.0
  Ca  Ca3  1  0.826  0.750  0.586  1.0
  Ni  Ni4  1  0.300  0.024  0.700  1.0
  Ni  Ni5  1  0.800  0.976  0.800  1.0
  Ni  Ni6  1  0.700  0.524  0.300  1.0
  Ni  Ni7  1  0.200  0.476  0.200  1.0
  Ni  Ni8  1  0.324  0.750  0.762  1.0
  Ni  Ni9  1  0.824  0.250  0.738  1.0
  Ni  Ni10  1  0.676  0.250  0.238  1.0
  Ni  Ni11  1  0.176  0.750  0.262  1.0
  Ni  Ni12  1  0.800  0.524  0.800  1.0
  Ni  Ni13  1  0.300  0.476  0.700  1.0
  Ni  Ni14  1  0.200  0.024  0.200  1.0
  Ni  Ni15  1  0.700  0.976  0.300  1.0
  O  O16  1  0.928  0.121  0.273  1.0
  O  O17  1  0.428  0.879  0.227  1.0
  O  O18  1  0.072  0.621  0.727  1.0
  O  O19  1  0.572  0.379  0.773  1.0
  O  O20  1  0.072  0.879  0.727  1.0
  O  O21  1  0.572  0.121  0.773  1.0
  O  O22  1  0.928  0.379  0.273  1.0
  O  O23  1  0.428  0.621  0.227  1.0
  O  O24  1  0.452  0.120  0.294  1.0
  O  O25  1  0.952  0.880  0.206  1.0
  O  O26  1  0.548  0.620  0.706  1.0
  O  O27  1  0.048  0.380  0.794  1.0
  O  O28  1  0.548  0.880  0.706  1.0
  O  O29  1  0.048  0.120  0.794  1.0
  O  O30  1  0.452  0.380  0.294  1.0
  O  O31  1  0.952  0.620  0.206  1.0
  O  O32  1  0.089  0.750  0.424  1.0
  O  O33  1  0.589  0.250  0.076  1.0
  O  O34  1  0.911  0.250  0.576  1.0
  O  O35  1  0.411  0.750  0.924  1.0
  O  O36  1  0.259  0.406  0.059  1.0
  O  O37  1  0.759  0.594  0.441  1.0
  O  O38  1  0.741  0.906  0.941  1.0
  O  O39  1  0.241  0.094  0.559  1.0
  O  O40  1  0.741  0.594  0.941  1.0
  O  O41  1  0.241  0.406  0.559  1.0
  O  O42  1  0.259  0.094  0.059  1.0
  O  O43  1  0.759  0.906  0.441  1.0
[/CIF]
.