data_Mo2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.8
_cell_length_b   4.8
_cell_length_c   7.17
_cell_angle_alpha   107.85
_cell_angle_beta   107.85
_cell_angle_gamma   38.13
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mo2Se
_chemical_formula_sum   'Mo4 Se2'
_cell_volume   96.48
_cell_formula_units_Z   2
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
  Mo  Mo0  1  0.39  0.0  0.84  1.0
  Mo  Mo1  1  0.12  0.0  0.56  1.0
  Mo  Mo2  1  0.36  0.0  0.94  1.0
  Mo  Mo3  1  0.63  0.0  0.21  1.0
  Se  Se4  1  0.86  0.0  0.45  1.0
  Se  Se5  1  0.89  0.0  0.32  1.0

data_Mo2Se
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.14
_cell_length_b   4.8
_cell_length_c   7.17
_cell_angle_alpha   107.85
_cell_angle_beta   90.0
_cell_angle_gamma   109.07
_symmetry_Int_Tables_number   2
_chemical_formula_structural   Mo2Se
_chemical_formula_sum   'Mo4 Se2'
_cell_volume   96.48
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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
  Mo  Mo0  2  0.0  0.24  0.68  1.0
  Mo  Mo1  2  0.0  0.49  0.05  1.0
  Se  Se2  2  0.0  0.02  0.44  1.0

Mo Mo Mo Mo Se Se
MoMoSe crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one molybdenum dimer molecule and one MoSe cluster. In the MoSe cluster, Mo(2) is bonded in a single-bond geometry to one Se(1) atom. The Mo(2)-Se(1) bond length is 1.26 Å. Se(1) is bonded in a distorted water-like geometry to one Mo(2) and one Se(1) atom. The Se(1)-Se(1) bond length is 0.98 Å.