The material structure described by Ni19Se20 crystallizes in the triclinic P-1 space group. There are eleven inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-51°. In the second Ni site, Ni(2) is bonded to one Se(1), one Se(2), one Se(3), one Se(5), one Se(7), and one Se(9) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. In the third Ni site, Ni(3) is bonded to two equivalent Se(1), two equivalent Se(4), and two equivalent Se(7) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. In the fourth Ni site, Ni(4) is bonded to one Se(10), one Se(5), one Se(6), one Se(9), and two equivalent Se(8) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the fifth Ni site, Ni(5) is bonded to one Se(1), one Se(2), one Se(4), one Se(6), one Se(8), and one Se(9) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the sixth Ni site, Ni(6) is bonded to one Se(10), one Se(2), one Se(3), one Se(4), one Se(7), and one Se(9) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. In the seventh Ni site, Ni(7) is bonded to one Se(10), one Se(2), one Se(7), one Se(8), and two equivalent Se(5) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. In the eighth Ni site, Ni(8) is bonded to one Se(10), one Se(3), one Se(5), one Se(8), and two equivalent Se(6) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. In the ninth Ni site, Ni(9) is bonded to one Se(1), one Se(3), one Se(4), one Se(6), one Se(7), and one Se(8) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. In the tenth Ni site, Ni(10) is bonded to one Se(2), one Se(5), one Se(6), one Se(7), and two equivalent Se(10) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the eleventh Ni site, Ni(11) is bonded to two equivalent Se(1), two equivalent Se(3), and two equivalent Se(9) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-52°. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Ni(1), one Ni(11), one Ni(2), one Ni(3), one Ni(5), and one Ni(9) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Ni(1), one Ni(10), one Ni(2), one Ni(5), one Ni(6), and one Ni(7) atom. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Ni(11), one Ni(2), one Ni(6), one Ni(8), and one Ni(9) atom. In the fourth Se site, Se(4) is bonded in a 5-coordinate geometry to one Ni(1), one Ni(3), one Ni(5), one Ni(6), and one Ni(9) atom. In the fifth Se site, Se(5) is bonded in a 6-coordinate geometry to one Ni(10), one Ni(2), one Ni(4), one Ni(8), and two equivalent Ni(7) atoms. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to one Ni(10), one Ni(4), one Ni(5), one Ni(9), and two equivalent Ni(8) atoms. In the seventh Se site, Se(7) is bonded in a 6-coordinate geometry to one Ni(10), one Ni(2), one Ni(3), one Ni(6), one Ni(7), and one Ni(9) atom. In the eighth Se site, Se(8) is bonded in a 6-coordinate geometry to one Ni(5), one Ni(7), one Ni(8), one Ni(9), and two equivalent Ni(4) atoms. In the ninth Se site, Se(9) is bonded in a 5-coordinate geometry to one Ni(11), one Ni(2), one Ni(4), one Ni(5), and one Ni(6) atom. In the tenth Se site, Se(10) is bonded in a 6-coordinate geometry to one Ni(4), one Ni(6), one Ni(7), one Ni(8), and two equivalent Ni(10) atoms. is represented by the CIF card [CIF]
data_Ni19Se20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.416
_cell_length_b   9.031
_cell_length_c   10.989
_cell_angle_alpha   66.391
_cell_angle_beta   80.564
_cell_angle_gamma   66.082
_symmetry_Int_Tables_number   1
_cell_volume   616.430
_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
  Ni  Ni0  1  0.000  0.500  0.000  1.0
  Ni  Ni1  1  0.405  0.087  0.206  1.0
  Ni  Ni2  1  0.500  0.500  0.000  1.0
  Ni  Ni3  1  0.791  0.704  0.399  1.0
  Ni  Ni4  1  0.903  0.605  0.198  1.0
  Ni  Ni5  1  0.908  0.091  0.190  1.0
  Ni  Ni6  1  0.209  0.296  0.601  1.0
  Ni  Ni7  1  0.297  0.202  0.398  1.0
  Ni  Ni8  1  0.304  0.704  0.401  1.0
  Ni  Ni9  1  0.393  0.604  0.198  1.0
  Ni  Ni10  1  0.595  0.913  0.794  1.0
  Ni  Ni11  1  0.703  0.798  0.602  1.0
  Ni  Ni12  1  0.805  0.196  0.396  1.0
  Ni  Ni13  1  0.696  0.296  0.599  1.0
  Ni  Ni14  1  0.097  0.395  0.802  1.0
  Ni  Ni15  1  0.195  0.804  0.604  1.0
  Ni  Ni16  1  0.092  0.909  0.810  1.0
  Ni  Ni17  1  0.500  0.000  0.000  1.0
  Ni  Ni18  1  0.607  0.396  0.802  1.0
  Se  Se19  1  0.648  0.688  0.034  1.0
  Se  Se20  1  0.053  0.279  0.230  1.0
  Se  Se21  1  0.253  0.913  0.170  1.0
  Se  Se22  1  0.152  0.680  0.031  1.0
  Se  Se23  1  0.447  0.883  0.441  1.0
  Se  Se24  1  0.652  0.514  0.366  1.0
  Se  Se25  1  0.553  0.280  0.230  1.0
  Se  Se26  1  0.849  0.485  0.633  1.0
  Se  Se27  1  0.750  0.914  0.170  1.0
  Se  Se28  1  0.048  0.118  0.569  1.0
  Se  Se29  1  0.151  0.515  0.367  1.0
  Se  Se30  1  0.952  0.882  0.431  1.0
  Se  Se31  1  0.250  0.086  0.830  1.0
  Se  Se32  1  0.447  0.720  0.770  1.0
  Se  Se33  1  0.348  0.486  0.634  1.0
  Se  Se34  1  0.553  0.117  0.559  1.0
  Se  Se35  1  0.848  0.320  0.969  1.0
  Se  Se36  1  0.747  0.087  0.830  1.0
  Se  Se37  1  0.947  0.721  0.770  1.0
  Se  Se38  1  0.352  0.312  0.966  1.0
[/CIF]
.
The material structure described by Ni19Se20 crystallizes in the triclinic P-1 space group. There are eleven inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-51°. In the second Ni site, Ni(2) is bonded to one Se(1), one Se(2), one Se(3), one Se(5), one Se(7), and one Se(9) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. In the third Ni site, Ni(3) is bonded to two equivalent Se(1), two equivalent Se(4), and two equivalent Se(7) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. In the fourth Ni site, Ni(4) is bonded to one Se(10), one Se(5), one Se(6), one Se(9), and two equivalent Se(8) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the fifth Ni site, Ni(5) is bonded to one Se(1), one Se(2), one Se(4), one Se(6), one Se(8), and one Se(9) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the sixth Ni site, Ni(6) is bonded to one Se(10), one Se(2), one Se(3), one Se(4), one Se(7), and one Se(9) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. In the seventh Ni site, Ni(7) is bonded to one Se(10), one Se(2), one Se(7), one Se(8), and two equivalent Se(5) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. In the eighth Ni site, Ni(8) is bonded to one Se(10), one Se(3), one Se(5), one Se(8), and two equivalent Se(6) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. In the ninth Ni site, Ni(9) is bonded to one Se(1), one Se(3), one Se(4), one Se(6), one Se(7), and one Se(8) atom to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. In the tenth Ni site, Ni(10) is bonded to one Se(2), one Se(5), one Se(6), one Se(7), and two equivalent Se(10) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the eleventh Ni site, Ni(11) is bonded to two equivalent Se(1), two equivalent Se(3), and two equivalent Se(9) atoms to form a mixture of distorted corner, face, and edge-sharing NiSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-52°. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Ni(1), one Ni(11), one Ni(2), one Ni(3), one Ni(5), and one Ni(9) atom. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Ni(1), one Ni(10), one Ni(2), one Ni(5), one Ni(6), and one Ni(7) atom. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Ni(11), one Ni(2), one Ni(6), one Ni(8), and one Ni(9) atom. In the fourth Se site, Se(4) is bonded in a 5-coordinate geometry to one Ni(1), one Ni(3), one Ni(5), one Ni(6), and one Ni(9) atom. In the fifth Se site, Se(5) is bonded in a 6-coordinate geometry to one Ni(10), one Ni(2), one Ni(4), one Ni(8), and two equivalent Ni(7) atoms. In the sixth Se site, Se(6) is bonded in a 6-coordinate geometry to one Ni(10), one Ni(4), one Ni(5), one Ni(9), and two equivalent Ni(8) atoms. In the seventh Se site, Se(7) is bonded in a 6-coordinate geometry to one Ni(10), one Ni(2), one Ni(3), one Ni(6), one Ni(7), and one Ni(9) atom. In the eighth Se site, Se(8) is bonded in a 6-coordinate geometry to one Ni(5), one Ni(7), one Ni(8), one Ni(9), and two equivalent Ni(4) atoms. In the ninth Se site, Se(9) is bonded in a 5-coordinate geometry to one Ni(11), one Ni(2), one Ni(4), one Ni(5), and one Ni(6) atom. In the tenth Se site, Se(10) is bonded in a 6-coordinate geometry to one Ni(4), one Ni(6), one Ni(7), one Ni(8), and two equivalent Ni(10) atoms. is represented by the CIF card [CIF]
data_Ni19Se20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.416
_cell_length_b   9.031
_cell_length_c   10.989
_cell_angle_alpha   66.391
_cell_angle_beta   80.564
_cell_angle_gamma   66.082
_symmetry_Int_Tables_number   1
_cell_volume   616.430
_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
  Ni  Ni0  1  0.000  0.500  0.000  1.0
  Ni  Ni1  1  0.405  0.087  0.206  1.0
  Ni  Ni2  1  0.500  0.500  0.000  1.0
  Ni  Ni3  1  0.791  0.704  0.399  1.0
  Ni  Ni4  1  0.903  0.605  0.198  1.0
  Ni  Ni5  1  0.908  0.091  0.190  1.0
  Ni  Ni6  1  0.209  0.296  0.601  1.0
  Ni  Ni7  1  0.297  0.202  0.398  1.0
  Ni  Ni8  1  0.304  0.704  0.401  1.0
  Ni  Ni9  1  0.393  0.604  0.198  1.0
  Ni  Ni10  1  0.595  0.913  0.794  1.0
  Ni  Ni11  1  0.703  0.798  0.602  1.0
  Ni  Ni12  1  0.805  0.196  0.396  1.0
  Ni  Ni13  1  0.696  0.296  0.599  1.0
  Ni  Ni14  1  0.097  0.395  0.802  1.0
  Ni  Ni15  1  0.195  0.804  0.604  1.0
  Ni  Ni16  1  0.092  0.909  0.810  1.0
  Ni  Ni17  1  0.500  0.000  0.000  1.0
  Ni  Ni18  1  0.607  0.396  0.802  1.0
  Se  Se19  1  0.648  0.688  0.034  1.0
  Se  Se20  1  0.053  0.279  0.230  1.0
  Se  Se21  1  0.253  0.913  0.170  1.0
  Se  Se22  1  0.152  0.680  0.031  1.0
  Se  Se23  1  0.447  0.883  0.441  1.0
  Se  Se24  1  0.652  0.514  0.366  1.0
  Se  Se25  1  0.553  0.280  0.230  1.0
  Se  Se26  1  0.849  0.485  0.633  1.0
  Se  Se27  1  0.750  0.914  0.170  1.0
  Se  Se28  1  0.048  0.118  0.569  1.0
  Se  Se29  1  0.151  0.515  0.367  1.0
  Se  Se30  1  0.952  0.882  0.431  1.0
  Se  Se31  1  0.250  0.086  0.830  1.0
  Se  Se32  1  0.447  0.720  0.770  1.0
  Se  Se33  1  0.348  0.486  0.634  1.0
  Se  Se34  1  0.553  0.117  0.559  1.0
  Se  Se35  1  0.848  0.320  0.969  1.0
  Se  Se36  1  0.747  0.087  0.830  1.0
  Se  Se37  1  0.947  0.721  0.770  1.0
  Se  Se38  1  0.352  0.312  0.966  1.0
[/CIF]
.