The structure described by Ca(NiO2)2 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(4), two equivalent O(2), and three equivalent O(3) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. In the second Ni site, Ni(2) is bonded to one O(2), two equivalent O(4), and three equivalent O(1) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Ni(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 square pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ca(1), one Ni(1), and two equivalent Ni(2) atoms. is represented by the CIF file [CIF]
data_Ca(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.968
_cell_length_b   8.886
_cell_length_c   10.339
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   272.707
_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  0.250  0.243  0.340  1.0
  Ca  Ca1  1  0.750  0.757  0.660  1.0
  Ca  Ca2  1  0.250  0.743  0.160  1.0
  Ca  Ca3  1  0.750  0.257  0.840  1.0
  Ni  Ni4  1  0.750  0.417  0.100  1.0
  Ni  Ni5  1  0.250  0.083  0.600  1.0
  Ni  Ni6  1  0.750  0.917  0.400  1.0
  Ni  Ni7  1  0.250  0.583  0.900  1.0
  Ni  Ni8  1  0.250  0.560  0.388  1.0
  Ni  Ni9  1  0.750  0.440  0.612  1.0
  Ni  Ni10  1  0.250  0.060  0.112  1.0
  Ni  Ni11  1  0.750  0.940  0.888  1.0
  O  O12  1  0.750  0.920  0.074  1.0
  O  O13  1  0.250  0.080  0.926  1.0
  O  O14  1  0.750  0.420  0.426  1.0
  O  O15  1  0.250  0.580  0.574  1.0
  O  O16  1  0.750  0.026  0.713  1.0
  O  O17  1  0.250  0.974  0.287  1.0
  O  O18  1  0.750  0.526  0.787  1.0
  O  O19  1  0.250  0.474  0.213  1.0
  O  O20  1  0.750  0.614  0.022  1.0
  O  O21  1  0.250  0.386  0.978  1.0
  O  O22  1  0.750  0.114  0.478  1.0
  O  O23  1  0.250  0.886  0.522  1.0
  O  O24  1  0.250  0.793  0.843  1.0
  O  O25  1  0.750  0.207  0.157  1.0
  O  O26  1  0.750  0.707  0.343  1.0
  O  O27  1  0.250  0.293  0.657  1.0
[/CIF]
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The structure described by Ca(NiO2)2 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(4), two equivalent O(2), and three equivalent O(3) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. In the second Ni site, Ni(2) is bonded to one O(2), two equivalent O(4), and three equivalent O(1) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Ni(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 square pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ca(1), one Ni(1), and two equivalent Ni(2) atoms. is represented by the CIF file [CIF]
data_Ca(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.968
_cell_length_b   8.886
_cell_length_c   10.339
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   272.707
_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  0.250  0.243  0.340  1.0
  Ca  Ca1  1  0.750  0.757  0.660  1.0
  Ca  Ca2  1  0.250  0.743  0.160  1.0
  Ca  Ca3  1  0.750  0.257  0.840  1.0
  Ni  Ni4  1  0.750  0.417  0.100  1.0
  Ni  Ni5  1  0.250  0.083  0.600  1.0
  Ni  Ni6  1  0.750  0.917  0.400  1.0
  Ni  Ni7  1  0.250  0.583  0.900  1.0
  Ni  Ni8  1  0.250  0.560  0.388  1.0
  Ni  Ni9  1  0.750  0.440  0.612  1.0
  Ni  Ni10  1  0.250  0.060  0.112  1.0
  Ni  Ni11  1  0.750  0.940  0.888  1.0
  O  O12  1  0.750  0.920  0.074  1.0
  O  O13  1  0.250  0.080  0.926  1.0
  O  O14  1  0.750  0.420  0.426  1.0
  O  O15  1  0.250  0.580  0.574  1.0
  O  O16  1  0.750  0.026  0.713  1.0
  O  O17  1  0.250  0.974  0.287  1.0
  O  O18  1  0.750  0.526  0.787  1.0
  O  O19  1  0.250  0.474  0.213  1.0
  O  O20  1  0.750  0.614  0.022  1.0
  O  O21  1  0.250  0.386  0.978  1.0
  O  O22  1  0.750  0.114  0.478  1.0
  O  O23  1  0.250  0.886  0.522  1.0
  O  O24  1  0.250  0.793  0.843  1.0
  O  O25  1  0.750  0.207  0.157  1.0
  O  O26  1  0.750  0.707  0.343  1.0
  O  O27  1  0.250  0.293  0.657  1.0
[/CIF]
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