data_Sr3SeN
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.19
_cell_length_b   5.19
_cell_length_c   5.19
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sr3SeN
_chemical_formula_sum   'Sr3 Se1 N1'
_cell_volume   139.42
_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
  Sr  Sr0  1  0.0  0.59  0.0  1.0
  Sr  Sr1  1  0.0  0.0  0.59  1.0
  Sr  Sr2  1  0.59  0.0  0.0  1.0
  Se  Se3  1  0.59  0.59  0.59  1.0
  N  N4  1  0.0  0.0  0.0  1.0

data_Sr3SeN
_symmetry_space_group_name_H-M   R3m
_cell_length_a   7.33
_cell_length_b   7.33
_cell_length_c   8.98
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Sr3SeN
_chemical_formula_sum   'Sr9 Se3 N3'
_cell_volume   418.25
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Sr  Sr0  9  0.06  0.53  0.53  1.0
  Se  Se1  3  0.0  0.0  0.59  1.0
  N  N2  3  0.0  0.0  0.0  1.0

Sr Sr Sr Se N
Sr3NSe crystallizes in the trigonal R3m space group. Sr(1) is bonded in a distorted single-bond geometry to two equivalent N(1) and three equivalent Se(1) atoms. There is one shorter (2.11 Å) and one longer (3.07 Å) Sr(1)-N(1) bond length. There is one shorter (2.99 Å) and two longer (3.73 Å) Sr(1)-Se(1) bond lengths. N(1) is bonded to six equivalent Sr(1) atoms to form distorted corner-sharing NSr6 octahedra. The corner-sharing octahedra are not tilted. Se(1) is bonded in a 9-coordinate geometry to nine equivalent Sr(1) atoms.