data_Tc2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.55
_cell_length_b   5.55
_cell_length_c   5.77
_cell_angle_alpha   102.26
_cell_angle_beta   102.26
_cell_angle_gamma   31.96
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Tc2Se
_chemical_formula_sum   'Tc4 Se2'
_cell_volume   91.62
_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
  Tc  Tc2  1  0.37  0.0  0.95  1.0
  Tc  Tc3  1  0.88  0.0  0.04  1.0
  Tc  Tc4  1  0.02  0.0  0.68  1.0
  Tc  Tc5  1  0.51  0.0  0.58  1.0
  Se  Se0  1  0.81  0.0  0.38  1.0
  Se  Se1  1  0.58  0.0  0.24  1.0

data_Tc2Se
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.05
_cell_length_b   5.55
_cell_length_c   5.77
_cell_angle_alpha   102.26
_cell_angle_beta   90.0
_cell_angle_gamma   105.98
_symmetry_Int_Tables_number   2
_chemical_formula_structural   Tc2Se
_chemical_formula_sum   'Tc4 Se2'
_cell_volume   91.62
_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
  Tc  Tc0  2  0.0  0.19  0.23  1.0
  Tc  Tc1  2  0.0  0.32  0.86  1.0
  Se  Se2  2  0.0  0.11  0.57  1.0

Tc Tc Tc Tc Se Se
Tc Tc Tc Tc Se Se 0 2 o o o 0 5 o o + 0 3 o o o 1 5 o o o 1 4 o o o 1 2 + o - 2 4 - o o 3 5 o o o 3 4 o o o 4 5 o o o 
Tc2Se crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one Tc2Se cluster. There are two inequivalent Tc sites. In the first Tc site, Tc(1) is bonded in a single-bond geometry to one Se(1) atom. The Tc(1)-Se(1) bond length is 1.85 Å. In the second Tc site, Tc(2) is bonded in a 2-coordinate geometry to two equivalent Se(1) atoms. There is one shorter (2.08 Å) and one longer (2.21 Å) Tc(2)-Se(1) bond length. Se(1) is bonded in a 4-coordinate geometry to one Tc(1), two equivalent Tc(2), and one Se(1) atom. The Se(1)-Se(1) bond length is 1.34 Å.