The compound described by Np2Se3 crystallizes in the tetragonal I-42d space group. There are three inequivalent Np sites. In the first Np site, Np(1) is bonded to two equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms to form a mixture of distorted edge, face, and corner-sharing NpSe8 hexagonal bipyramids. In the second Np site, Np(2) is bonded to two equivalent Se(1), two equivalent Se(3), and four equivalent Se(2) atoms to form a mixture of distorted edge, face, and corner-sharing NpSe8 hexagonal bipyramids. In the third Np site, Np(3) is bonded to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms to form a mixture of distorted edge, face, and corner-sharing NpSe8 hexagonal bipyramids. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Np(2), two equivalent Np(1), and two equivalent Np(3) atoms to form SeNp5 square pyramids that share corners with five equivalent Se(2)Np6 octahedra, corners with four equivalent Se(1)Np5 square pyramids, corners with four equivalent Se(3)Np5 square pyramids, edges with three equivalent Se(2)Np6 octahedra,  an edgeedge with one Se(1)Np5 square pyramid, edges with four equivalent Se(3)Np5 square pyramids,  a faceface with one Se(2)Np6 octahedra, and  a faceface with one Se(1)Np5 square pyramid. The corner-sharing octahedral tilt angles range from 19-47°. In the second Se site, Se(2) is bonded to one Np(3), two equivalent Np(2), and three equivalent Np(1) atoms to form distorted SeNp6 octahedra that share corners with three equivalent Se(2)Np6 octahedra, corners with five equivalent Se(1)Np5 square pyramids, corners with seven equivalent Se(3)Np5 square pyramids, edges with two equivalent Se(2)Np6 octahedra,  an edgeedge with one Se(3)Np5 square pyramid, edges with three equivalent Se(1)Np5 square pyramids, faces with two equivalent Se(2)Np6 octahedra,  a faceface with one Se(1)Np5 square pyramid, and faces with two equivalent Se(3)Np5 square pyramids. The corner-sharing octahedral tilt angles range from 16-51°. In the third Se site, Se(3) is bonded to one Np(2), one Np(3), and three equivalent Np(1) atoms to form distorted SeNp5 square pyramids that share corners with seven equivalent Se(2)Np6 octahedra, corners with four equivalent Se(1)Np5 square pyramids, corners with five equivalent Se(3)Np5 square pyramids,  an edgeedge with one Se(2)Np6 octahedra, edges with four equivalent Se(1)Np5 square pyramids, faces with two equivalent Se(2)Np6 octahedra, and  a faceface with one Se(3)Np5 square pyramid. The corner-sharing octahedral tilt angles range from 14-52°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Np2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   22.496
_cell_length_b   8.663
_cell_length_c   8.663
_cell_angle_alpha   90.000
_cell_angle_beta   54.717
_cell_angle_gamma   54.717
_symmetry_Int_Tables_number   1
_cell_volume   973.745
_cell_formula_units_Z   8
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
  Np  Np0  1  0.998  0.384  0.252  1.0
  Np  Np1  1  0.998  0.123  0.755  1.0
  Np  Np2  1  0.082  0.627  0.377  1.0
  Np  Np3  1  0.167  0.250  0.632  1.0
  Np  Np4  1  0.336  0.377  0.248  1.0
  Np  Np5  1  0.252  0.873  0.123  1.0
  Np  Np6  1  0.167  0.750  0.868  1.0
  Np  Np7  1  0.336  0.116  0.745  1.0
  Np  Np8  1  0.498  0.255  0.623  1.0
  Np  Np9  1  0.667  0.368  0.250  1.0
  Np  Np10  1  0.582  0.877  0.127  1.0
  Np  Np11  1  0.498  0.752  0.884  1.0
  Np  Np12  1  0.667  0.132  0.750  1.0
  Np  Np13  1  0.752  0.623  0.373  1.0
  Np  Np14  1  0.836  0.245  0.616  1.0
  Np  Np15  1  0.836  0.748  0.877  1.0
  Se  Se16  1  0.120  0.493  0.997  1.0
  Se  Se17  1  0.051  0.347  0.499  1.0
  Se  Se18  1  0.282  0.153  0.153  1.0
  Se  Se19  1  0.051  1.000  0.347  1.0
  Se  Se20  1  0.282  0.500  0.001  1.0
  Se  Se21  1  0.213  0.007  0.858  1.0
  Se  Se22  1  0.120  0.646  0.642  1.0
  Se  Se23  1  0.213  0.854  0.503  1.0
  Se  Se24  1  0.449  0.499  0.998  1.0
  Se  Se25  1  0.385  0.344  0.501  1.0
  Se  Se26  1  0.620  0.142  0.146  1.0
  Se  Se27  1  0.385  0.002  0.345  1.0
  Se  Se28  1  0.620  0.497  0.993  1.0
  Se  Se29  1  0.551  0.999  0.847  1.0
  Se  Se30  1  0.449  0.655  0.656  1.0
  Se  Se31  1  0.551  0.847  0.500  1.0
  Se  Se32  1  0.782  0.501  0.000  1.0
  Se  Se33  1  0.713  0.358  0.507  1.0
  Se  Se34  1  0.949  0.156  0.155  1.0
  Se  Se35  1  0.713  0.003  0.354  1.0
  Se  Se36  1  0.949  0.498  0.999  1.0
  Se  Se37  1  0.885  0.001  0.844  1.0
  Se  Se38  1  0.782  0.653  0.653  1.0
  Se  Se39  1  0.885  0.845  0.502  1.0
[/CIF]
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The compound described by Np2Se3 crystallizes in the tetragonal I-42d space group. There are three inequivalent Np sites. In the first Np site, Np(1) is bonded to two equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms to form a mixture of distorted edge, face, and corner-sharing NpSe8 hexagonal bipyramids. In the second Np site, Np(2) is bonded to two equivalent Se(1), two equivalent Se(3), and four equivalent Se(2) atoms to form a mixture of distorted edge, face, and corner-sharing NpSe8 hexagonal bipyramids. In the third Np site, Np(3) is bonded to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms to form a mixture of distorted edge, face, and corner-sharing NpSe8 hexagonal bipyramids. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Np(2), two equivalent Np(1), and two equivalent Np(3) atoms to form SeNp5 square pyramids that share corners with five equivalent Se(2)Np6 octahedra, corners with four equivalent Se(1)Np5 square pyramids, corners with four equivalent Se(3)Np5 square pyramids, edges with three equivalent Se(2)Np6 octahedra,  an edgeedge with one Se(1)Np5 square pyramid, edges with four equivalent Se(3)Np5 square pyramids,  a faceface with one Se(2)Np6 octahedra, and  a faceface with one Se(1)Np5 square pyramid. The corner-sharing octahedral tilt angles range from 19-47°. In the second Se site, Se(2) is bonded to one Np(3), two equivalent Np(2), and three equivalent Np(1) atoms to form distorted SeNp6 octahedra that share corners with three equivalent Se(2)Np6 octahedra, corners with five equivalent Se(1)Np5 square pyramids, corners with seven equivalent Se(3)Np5 square pyramids, edges with two equivalent Se(2)Np6 octahedra,  an edgeedge with one Se(3)Np5 square pyramid, edges with three equivalent Se(1)Np5 square pyramids, faces with two equivalent Se(2)Np6 octahedra,  a faceface with one Se(1)Np5 square pyramid, and faces with two equivalent Se(3)Np5 square pyramids. The corner-sharing octahedral tilt angles range from 16-51°. In the third Se site, Se(3) is bonded to one Np(2), one Np(3), and three equivalent Np(1) atoms to form distorted SeNp5 square pyramids that share corners with seven equivalent Se(2)Np6 octahedra, corners with four equivalent Se(1)Np5 square pyramids, corners with five equivalent Se(3)Np5 square pyramids,  an edgeedge with one Se(2)Np6 octahedra, edges with four equivalent Se(1)Np5 square pyramids, faces with two equivalent Se(2)Np6 octahedra, and  a faceface with one Se(3)Np5 square pyramid. The corner-sharing octahedral tilt angles range from 14-52°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Np2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   22.496
_cell_length_b   8.663
_cell_length_c   8.663
_cell_angle_alpha   90.000
_cell_angle_beta   54.717
_cell_angle_gamma   54.717
_symmetry_Int_Tables_number   1
_cell_volume   973.745
_cell_formula_units_Z   8
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
  Np  Np0  1  0.998  0.384  0.252  1.0
  Np  Np1  1  0.998  0.123  0.755  1.0
  Np  Np2  1  0.082  0.627  0.377  1.0
  Np  Np3  1  0.167  0.250  0.632  1.0
  Np  Np4  1  0.336  0.377  0.248  1.0
  Np  Np5  1  0.252  0.873  0.123  1.0
  Np  Np6  1  0.167  0.750  0.868  1.0
  Np  Np7  1  0.336  0.116  0.745  1.0
  Np  Np8  1  0.498  0.255  0.623  1.0
  Np  Np9  1  0.667  0.368  0.250  1.0
  Np  Np10  1  0.582  0.877  0.127  1.0
  Np  Np11  1  0.498  0.752  0.884  1.0
  Np  Np12  1  0.667  0.132  0.750  1.0
  Np  Np13  1  0.752  0.623  0.373  1.0
  Np  Np14  1  0.836  0.245  0.616  1.0
  Np  Np15  1  0.836  0.748  0.877  1.0
  Se  Se16  1  0.120  0.493  0.997  1.0
  Se  Se17  1  0.051  0.347  0.499  1.0
  Se  Se18  1  0.282  0.153  0.153  1.0
  Se  Se19  1  0.051  1.000  0.347  1.0
  Se  Se20  1  0.282  0.500  0.001  1.0
  Se  Se21  1  0.213  0.007  0.858  1.0
  Se  Se22  1  0.120  0.646  0.642  1.0
  Se  Se23  1  0.213  0.854  0.503  1.0
  Se  Se24  1  0.449  0.499  0.998  1.0
  Se  Se25  1  0.385  0.344  0.501  1.0
  Se  Se26  1  0.620  0.142  0.146  1.0
  Se  Se27  1  0.385  0.002  0.345  1.0
  Se  Se28  1  0.620  0.497  0.993  1.0
  Se  Se29  1  0.551  0.999  0.847  1.0
  Se  Se30  1  0.449  0.655  0.656  1.0
  Se  Se31  1  0.551  0.847  0.500  1.0
  Se  Se32  1  0.782  0.501  0.000  1.0
  Se  Se33  1  0.713  0.358  0.507  1.0
  Se  Se34  1  0.949  0.156  0.155  1.0
  Se  Se35  1  0.713  0.003  0.354  1.0
  Se  Se36  1  0.949  0.498  0.999  1.0
  Se  Se37  1  0.885  0.001  0.844  1.0
  Se  Se38  1  0.782  0.653  0.653  1.0
  Se  Se39  1  0.885  0.845  0.502  1.0
[/CIF]
.