data_MgSi2Ni
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.29
_cell_length_b   5.29
_cell_length_c   5.29
_cell_angle_alpha   150.71
_cell_angle_beta   126.01
_cell_angle_gamma   62.6
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgSi2Ni
_chemical_formula_sum   'Mg1 Si2 Ni1'
_cell_volume   58.05
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Si  Si2  1  0.0  0.4  0.95  1.0
  Si  Si3  1  0.34  0.0  0.57  1.0
  Ni  Ni1  1  0.0  0.0  0.52  1.0

data_MgSi2Ni
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.67
_cell_length_b   4.8
_cell_length_c   5.29
_cell_angle_alpha   116.99
_cell_angle_beta   104.64
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgSi2Ni
_chemical_formula_sum   'Mg1 Si2 Ni1'
_cell_volume   58.05
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Si  Si1  1  0.05  0.45  0.45  1.0
  Si  Si2  1  0.77  0.43  0.77  1.0
  Ni  Ni3  1  0.48  0.48  0.48  1.0

Mg Si Si Ni
Mg Si Si Ni 0 1 o o - 0 1 o - - 0 2 - o - 0 2 o o o 0 0 o + + 0 3 o o - 0 3 o o o 1 3 o o o 2 3 o o o 
MgNiSi2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Ni(1), two equivalent Si(1), and two equivalent Si(2) atoms. Both Mg(1)-Mg(1) bond lengths are 2.67 Å. There is one shorter (2.54 Å) and one longer (2.75 Å) Mg(1)-Ni(1) bond length. There is one shorter (2.36 Å) and one longer (2.94 Å) Mg(1)-Si(1) bond length. There is one shorter (2.44 Å) and one longer (2.84 Å) Mg(1)-Si(2) bond length. Ni(1) is bonded in a 5-coordinate geometry to two equivalent Mg(1), one Si(2), and two equivalent Si(1) atoms. The Ni(1)-Si(2) bond length is 1.64 Å. There is one shorter (1.12 Å) and one longer (1.57 Å) Ni(1)-Si(1) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and two equivalent Ni(1) atoms. In the second Si site, Si(2) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and one Ni(1) atom.