The compound described by CaSi4(NiO6)2 crystallizes in the monoclinic C2 space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-61°. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-58°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ni(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(1), one Ni(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), one Ni(1), one Ni(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_CaSi4(NiO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.555
_cell_length_b   6.555
_cell_length_c   5.298
_cell_angle_alpha   77.502
_cell_angle_beta   77.502
_cell_angle_gamma   84.318
_symmetry_Int_Tables_number   1
_cell_volume   216.617
_cell_formula_units_Z   1
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  0.302  0.698  0.000  1.0
  Si  Si1  1  0.384  0.200  0.020  1.0
  Si  Si2  1  0.800  0.616  0.980  1.0
  Si  Si3  1  0.200  0.379  0.531  1.0
  Si  Si4  1  0.621  0.800  0.469  1.0
  Ni  Ni5  1  0.898  0.102  0.000  1.0
  Ni  Ni6  1  0.088  0.912  0.500  1.0
  O  O7  1  0.357  0.340  0.251  1.0
  O  O8  1  0.660  0.643  0.749  1.0
  O  O9  1  0.623  0.665  0.240  1.0
  O  O10  1  0.335  0.377  0.760  1.0
  O  O11  1  0.616  0.092  0.956  1.0
  O  O12  1  0.908  0.384  0.044  1.0
  O  O13  1  0.383  0.893  0.563  1.0
  O  O14  1  0.107  0.617  0.437  1.0
  O  O15  1  0.036  0.189  0.629  1.0
  O  O16  1  0.811  0.964  0.371  1.0
  O  O17  1  0.200  0.030  0.104  1.0
  O  O18  1  0.970  0.800  0.896  1.0
[/CIF]
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The compound described by CaSi4(NiO6)2 crystallizes in the monoclinic C2 space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-61°. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-58°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ni(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(1), one Ni(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), one Ni(1), one Ni(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_CaSi4(NiO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.555
_cell_length_b   6.555
_cell_length_c   5.298
_cell_angle_alpha   77.502
_cell_angle_beta   77.502
_cell_angle_gamma   84.318
_symmetry_Int_Tables_number   1
_cell_volume   216.617
_cell_formula_units_Z   1
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  0.302  0.698  0.000  1.0
  Si  Si1  1  0.384  0.200  0.020  1.0
  Si  Si2  1  0.800  0.616  0.980  1.0
  Si  Si3  1  0.200  0.379  0.531  1.0
  Si  Si4  1  0.621  0.800  0.469  1.0
  Ni  Ni5  1  0.898  0.102  0.000  1.0
  Ni  Ni6  1  0.088  0.912  0.500  1.0
  O  O7  1  0.357  0.340  0.251  1.0
  O  O8  1  0.660  0.643  0.749  1.0
  O  O9  1  0.623  0.665  0.240  1.0
  O  O10  1  0.335  0.377  0.760  1.0
  O  O11  1  0.616  0.092  0.956  1.0
  O  O12  1  0.908  0.384  0.044  1.0
  O  O13  1  0.383  0.893  0.563  1.0
  O  O14  1  0.107  0.617  0.437  1.0
  O  O15  1  0.036  0.189  0.629  1.0
  O  O16  1  0.811  0.964  0.371  1.0
  O  O17  1  0.200  0.030  0.104  1.0
  O  O18  1  0.970  0.800  0.896  1.0
[/CIF]
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