The material described by Na2Mg2NiH6 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one H(3), two equivalent H(2), and two equivalent H(4) atoms. In the second Na site, Na(2) is bonded to one H(1), one H(3), two equivalent H(2), and two equivalent H(4) atoms to form distorted NaH6 pentagonal pyramids that share corners with four equivalent Mg(1)H6 octahedra, corners with two equivalent Ni(1)H4 tetrahedra, edges with four equivalent Mg(1)H6 octahedra, and  an edgeedge with one Ni(1)H4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-81°. Mg(1) is bonded to one H(1), one H(3), two equivalent H(2), and two equivalent H(4) atoms to form distorted MgH6 octahedra that share corners with four equivalent Mg(1)H6 octahedra, corners with two equivalent Na(2)H6 pentagonal pyramids,  an edgeedge with one Mg(1)H6 octahedra, edges with two equivalent Na(2)H6 pentagonal pyramids, and edges with two equivalent Ni(1)H4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-33°. Ni(1) is bonded to one H(1), one H(3), and two equivalent H(2) atoms to form NiH4 tetrahedra that share corners with two equivalent Na(2)H6 pentagonal pyramids, edges with four equivalent Mg(1)H6 octahedra, and  an edgeedge with one Na(2)H6 pentagonal pyramid. There are four inequivalent H sites. In the first H site, H(3) is bonded to one Na(1), one Na(2), two equivalent Mg(1), and one Ni(1) atom to form a mixture of distorted edge and corner-sharing HNa2Mg2Ni trigonal bipyramids. In the second H site, H(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), and two equivalent Mg(1) atoms. In the third H site, H(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), two equivalent Mg(1), and one Ni(1) atom. In the fourth H site, H(2) is bonded to one Na(1), one Na(2), two equivalent Mg(1), and one Ni(1) atom to form a mixture of distorted edge, corner, and face-sharing HNa2Mg2Ni square pyramids. is represented by the CIF file [CIF]
data_Na2Mg2NiH6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.408
_cell_length_b   8.419
_cell_length_c   11.382
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   518.206
_cell_formula_units_Z   4
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
  Na  Na0  1  0.953  0.750  0.391  1.0
  Na  Na1  1  0.547  0.750  0.891  1.0
  Na  Na2  1  0.047  0.250  0.609  1.0
  Na  Na3  1  0.453  0.250  0.109  1.0
  Na  Na4  1  0.445  0.750  0.168  1.0
  Na  Na5  1  0.055  0.750  0.668  1.0
  Na  Na6  1  0.555  0.250  0.832  1.0
  Na  Na7  1  0.945  0.250  0.332  1.0
  Mg  Mg8  1  0.440  0.493  0.372  1.0
  Mg  Mg9  1  0.060  0.007  0.872  1.0
  Mg  Mg10  1  0.560  0.993  0.628  1.0
  Mg  Mg11  1  0.940  0.507  0.128  1.0
  Mg  Mg12  1  0.560  0.507  0.628  1.0
  Mg  Mg13  1  0.940  0.993  0.128  1.0
  Mg  Mg14  1  0.440  0.007  0.372  1.0
  Mg  Mg15  1  0.060  0.493  0.872  1.0
  Ni  Ni16  1  0.061  0.750  0.001  1.0
  Ni  Ni17  1  0.439  0.750  0.501  1.0
  Ni  Ni18  1  0.939  0.250  0.999  1.0
  Ni  Ni19  1  0.561  0.250  0.499  1.0
  H  H20  1  0.848  0.750  0.096  1.0
  H  H21  1  0.652  0.750  0.596  1.0
  H  H22  1  0.152  0.250  0.904  1.0
  H  H23  1  0.348  0.250  0.404  1.0
  H  H24  1  0.236  0.601  0.022  1.0
  H  H25  1  0.264  0.899  0.522  1.0
  H  H26  1  0.764  0.101  0.978  1.0
  H  H27  1  0.736  0.399  0.478  1.0
  H  H28  1  0.764  0.399  0.978  1.0
  H  H29  1  0.736  0.101  0.478  1.0
  H  H30  1  0.236  0.899  0.022  1.0
  H  H31  1  0.264  0.601  0.522  1.0
  H  H32  1  0.975  0.750  0.869  1.0
  H  H33  1  0.525  0.750  0.369  1.0
  H  H34  1  0.025  0.250  0.131  1.0
  H  H35  1  0.475  0.250  0.631  1.0
  H  H36  1  0.136  0.506  0.275  1.0
  H  H37  1  0.364  0.994  0.775  1.0
  H  H38  1  0.864  0.006  0.725  1.0
  H  H39  1  0.636  0.494  0.225  1.0
  H  H40  1  0.864  0.494  0.725  1.0
  H  H41  1  0.636  0.006  0.225  1.0
  H  H42  1  0.136  0.994  0.275  1.0
  H  H43  1  0.364  0.506  0.775  1.0
[/CIF]
.
The material described by Na2Mg2NiH6 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one H(3), two equivalent H(2), and two equivalent H(4) atoms. In the second Na site, Na(2) is bonded to one H(1), one H(3), two equivalent H(2), and two equivalent H(4) atoms to form distorted NaH6 pentagonal pyramids that share corners with four equivalent Mg(1)H6 octahedra, corners with two equivalent Ni(1)H4 tetrahedra, edges with four equivalent Mg(1)H6 octahedra, and  an edgeedge with one Ni(1)H4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-81°. Mg(1) is bonded to one H(1), one H(3), two equivalent H(2), and two equivalent H(4) atoms to form distorted MgH6 octahedra that share corners with four equivalent Mg(1)H6 octahedra, corners with two equivalent Na(2)H6 pentagonal pyramids,  an edgeedge with one Mg(1)H6 octahedra, edges with two equivalent Na(2)H6 pentagonal pyramids, and edges with two equivalent Ni(1)H4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-33°. Ni(1) is bonded to one H(1), one H(3), and two equivalent H(2) atoms to form NiH4 tetrahedra that share corners with two equivalent Na(2)H6 pentagonal pyramids, edges with four equivalent Mg(1)H6 octahedra, and  an edgeedge with one Na(2)H6 pentagonal pyramid. There are four inequivalent H sites. In the first H site, H(3) is bonded to one Na(1), one Na(2), two equivalent Mg(1), and one Ni(1) atom to form a mixture of distorted edge and corner-sharing HNa2Mg2Ni trigonal bipyramids. In the second H site, H(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), and two equivalent Mg(1) atoms. In the third H site, H(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), two equivalent Mg(1), and one Ni(1) atom. In the fourth H site, H(2) is bonded to one Na(1), one Na(2), two equivalent Mg(1), and one Ni(1) atom to form a mixture of distorted edge, corner, and face-sharing HNa2Mg2Ni square pyramids. is represented by the CIF file [CIF]
data_Na2Mg2NiH6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.408
_cell_length_b   8.419
_cell_length_c   11.382
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   518.206
_cell_formula_units_Z   4
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
  Na  Na0  1  0.953  0.750  0.391  1.0
  Na  Na1  1  0.547  0.750  0.891  1.0
  Na  Na2  1  0.047  0.250  0.609  1.0
  Na  Na3  1  0.453  0.250  0.109  1.0
  Na  Na4  1  0.445  0.750  0.168  1.0
  Na  Na5  1  0.055  0.750  0.668  1.0
  Na  Na6  1  0.555  0.250  0.832  1.0
  Na  Na7  1  0.945  0.250  0.332  1.0
  Mg  Mg8  1  0.440  0.493  0.372  1.0
  Mg  Mg9  1  0.060  0.007  0.872  1.0
  Mg  Mg10  1  0.560  0.993  0.628  1.0
  Mg  Mg11  1  0.940  0.507  0.128  1.0
  Mg  Mg12  1  0.560  0.507  0.628  1.0
  Mg  Mg13  1  0.940  0.993  0.128  1.0
  Mg  Mg14  1  0.440  0.007  0.372  1.0
  Mg  Mg15  1  0.060  0.493  0.872  1.0
  Ni  Ni16  1  0.061  0.750  0.001  1.0
  Ni  Ni17  1  0.439  0.750  0.501  1.0
  Ni  Ni18  1  0.939  0.250  0.999  1.0
  Ni  Ni19  1  0.561  0.250  0.499  1.0
  H  H20  1  0.848  0.750  0.096  1.0
  H  H21  1  0.652  0.750  0.596  1.0
  H  H22  1  0.152  0.250  0.904  1.0
  H  H23  1  0.348  0.250  0.404  1.0
  H  H24  1  0.236  0.601  0.022  1.0
  H  H25  1  0.264  0.899  0.522  1.0
  H  H26  1  0.764  0.101  0.978  1.0
  H  H27  1  0.736  0.399  0.478  1.0
  H  H28  1  0.764  0.399  0.978  1.0
  H  H29  1  0.736  0.101  0.478  1.0
  H  H30  1  0.236  0.899  0.022  1.0
  H  H31  1  0.264  0.601  0.522  1.0
  H  H32  1  0.975  0.750  0.869  1.0
  H  H33  1  0.525  0.750  0.369  1.0
  H  H34  1  0.025  0.250  0.131  1.0
  H  H35  1  0.475  0.250  0.631  1.0
  H  H36  1  0.136  0.506  0.275  1.0
  H  H37  1  0.364  0.994  0.775  1.0
  H  H38  1  0.864  0.006  0.725  1.0
  H  H39  1  0.636  0.494  0.225  1.0
  H  H40  1  0.864  0.494  0.725  1.0
  H  H41  1  0.636  0.006  0.225  1.0
  H  H42  1  0.136  0.994  0.275  1.0
  H  H43  1  0.364  0.506  0.775  1.0
[/CIF]
.