data_NpAs3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.64
_cell_length_b   5.64
_cell_length_c   5.64
_cell_angle_alpha   138.01
_cell_angle_beta   138.01
_cell_angle_gamma   60.88
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NpAs3
_chemical_formula_sum   'Np1 As3'
_cell_volume   79.34
_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
  Np  Np0  1  0.0  0.0  0.86  1.0
  As  As1  1  0.02  0.0  0.43  1.0
  As  As2  1  0.0  0.02  0.43  1.0
  As  As3  1  0.0  0.0  0.0  1.0

data_NpAs3
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.71
_cell_length_b   5.71
_cell_length_c   5.64
_cell_angle_alpha   90.0
_cell_angle_beta   120.44
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NpAs3
_chemical_formula_sum   'Np2 As6'
_cell_volume   158.68
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  2  0.0  0.0  0.86  1.0
  As  As1  4  0.49  0.49  0.41  1.0
  As  As2  2  0.0  0.0  0.0  1.0

Np As As As
Np As As As 0 3 o o + 1 2 o o o 
NpAs(As)2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two arsenic molecules and two NpAs clusters. In each NpAs cluster, Np(1) is bonded in a single-bond geometry to one As(2) atom. The Np(1)-As(2) bond length is 0.78 Å. As(2) is bonded in a single-bond geometry to one Np(1) atom.