The material described by Mg2NiH4 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded in a 8-coordinate geometry to two equivalent H(1), two equivalent H(2), two equivalent H(3), and two equivalent H(4) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a square co-planar geometry to two equivalent H(1) and two equivalent H(2) atoms. In the second Ni site, Ni(2) is bonded in a square co-planar geometry to two equivalent H(3) and two equivalent H(4) atoms. There are four inequivalent H sites. In the first H site, H(1) is bonded to four equivalent Mg(1) and one Ni(1) atom to form a mixture of distorted corner and edge-sharing HMg4Ni square pyramids. In the second H site, H(2) is bonded in a 1-coordinate geometry to four equivalent Mg(1) and one Ni(1) atom. In the third H site, H(3) is bonded to four equivalent Mg(1) and one Ni(2) atom to form a mixture of distorted corner, face, and edge-sharing HMg4Ni square pyramids. In the fourth H site, H(4) is bonded to four equivalent Mg(1) and one Ni(2) atom to form a mixture of distorted corner, face, and edge-sharing HMg4Ni square pyramids. is represented by the CIF file [CIF]
data_Mg2NiH4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.431
_cell_length_b   4.431
_cell_length_c   6.577
_cell_angle_alpha   89.634
_cell_angle_beta   89.634
_cell_angle_gamma   91.878
_symmetry_Int_Tables_number   1
_cell_volume   129.058
_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
  Mg  Mg0  1  0.003  0.506  0.745  1.0
  Mg  Mg1  1  0.506  0.003  0.745  1.0
  Mg  Mg2  1  0.997  0.494  0.255  1.0
  Mg  Mg3  1  0.494  0.997  0.255  1.0
  Ni  Ni4  1  0.000  0.000  0.000  1.0
  Ni  Ni5  1  0.500  0.500  0.500  1.0
  H  H6  1  0.760  0.240  0.000  1.0
  H  H7  1  0.240  0.760  0.000  1.0
  H  H8  1  0.250  0.250  0.983  1.0
  H  H9  1  0.750  0.750  0.017  1.0
  H  H10  1  0.483  0.483  0.266  1.0
  H  H11  1  0.517  0.517  0.734  1.0
  H  H12  1  0.249  0.249  0.518  1.0
  H  H13  1  0.751  0.751  0.482  1.0
[/CIF]
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The material described by Mg2NiH4 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded in a 8-coordinate geometry to two equivalent H(1), two equivalent H(2), two equivalent H(3), and two equivalent H(4) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a square co-planar geometry to two equivalent H(1) and two equivalent H(2) atoms. In the second Ni site, Ni(2) is bonded in a square co-planar geometry to two equivalent H(3) and two equivalent H(4) atoms. There are four inequivalent H sites. In the first H site, H(1) is bonded to four equivalent Mg(1) and one Ni(1) atom to form a mixture of distorted corner and edge-sharing HMg4Ni square pyramids. In the second H site, H(2) is bonded in a 1-coordinate geometry to four equivalent Mg(1) and one Ni(1) atom. In the third H site, H(3) is bonded to four equivalent Mg(1) and one Ni(2) atom to form a mixture of distorted corner, face, and edge-sharing HMg4Ni square pyramids. In the fourth H site, H(4) is bonded to four equivalent Mg(1) and one Ni(2) atom to form a mixture of distorted corner, face, and edge-sharing HMg4Ni square pyramids. is represented by the CIF file [CIF]
data_Mg2NiH4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.431
_cell_length_b   4.431
_cell_length_c   6.577
_cell_angle_alpha   89.634
_cell_angle_beta   89.634
_cell_angle_gamma   91.878
_symmetry_Int_Tables_number   1
_cell_volume   129.058
_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
  Mg  Mg0  1  0.003  0.506  0.745  1.0
  Mg  Mg1  1  0.506  0.003  0.745  1.0
  Mg  Mg2  1  0.997  0.494  0.255  1.0
  Mg  Mg3  1  0.494  0.997  0.255  1.0
  Ni  Ni4  1  0.000  0.000  0.000  1.0
  Ni  Ni5  1  0.500  0.500  0.500  1.0
  H  H6  1  0.760  0.240  0.000  1.0
  H  H7  1  0.240  0.760  0.000  1.0
  H  H8  1  0.250  0.250  0.983  1.0
  H  H9  1  0.750  0.750  0.017  1.0
  H  H10  1  0.483  0.483  0.266  1.0
  H  H11  1  0.517  0.517  0.734  1.0
  H  H12  1  0.249  0.249  0.518  1.0
  H  H13  1  0.751  0.751  0.482  1.0
[/CIF]
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