data_Ta3Tc
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.22
_cell_length_b   3.22
_cell_length_c   6.63
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ta3Tc
_chemical_formula_sum   'Ta3 Tc1'
_cell_volume   68.7
_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
  Ta  Ta0  1  0.61  0.61  0.05  1.0
  Ta  Ta1  1  0.61  0.61  0.58  1.0
  Ta  Ta2  1  0.0  0.0  0.31  1.0
  Tc  Tc3  1  0.0  0.0  0.0  1.0

data_Ta3Tc
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.55
_cell_length_b   4.55
_cell_length_c   6.63
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ta3Tc
_chemical_formula_sum   'Ta6 Tc2'
_cell_volume   137.39
_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
  Ta  Ta0  2  0.0  0.0  0.31  1.0
  Ta  Ta1  2  0.11  0.5  0.05  1.0
  Ta  Ta2  2  0.11  0.5  0.58  1.0
  Tc  Tc3  2  0.0  0.0  0.0  1.0

Ta Ta Ta Tc
Ta Ta Ta Tc 0 3 + + o 0 1 o o - 0 2 + + o 1 2 o o o 1 2 o + o 1 2 + o o 1 2 + + o 1 1 + o o 1 1 o + o 1 3 + + + 2 3 o o o 
Ta3Tc crystallizes in the monoclinic Cm space group. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 1-coordinate geometry to one Ta(2) and three equivalent Tc(1) atoms. The Ta(1)-Ta(2) bond length is 3.10 Å. There is one shorter (1.81 Å) and two longer (2.35 Å) Ta(1)-Tc(1) bond lengths. In the second Ta site, Ta(2) is bonded in a 12-coordinate geometry to one Ta(1), four equivalent Ta(2), four equivalent Ta(3), and three equivalent Tc(1) atoms. All Ta(2)-Ta(2) bond lengths are 3.22 Å. There are a spread of Ta(2)-Ta(3) bond distances ranging from 2.50-3.29 Å. There is one shorter (3.30 Å) and two longer (3.63 Å) Ta(2)-Tc(1) bond lengths. In the third Ta site, Ta(3) is bonded in a distorted single-bond geometry to four equivalent Ta(2) and one Tc(1) atom. The Ta(3)-Tc(1) bond length is 2.08 Å. Tc(1) is bonded in a 4-coordinate geometry to one Ta(3), three equivalent Ta(1), and three equivalent Ta(2) atoms.