The structure described by NaCaH3 is Ilmenite-like structured and crystallizes in the trigonal R3c space group. Na(1) is bonded to six equivalent H(1) atoms to form distorted NaH6 pentagonal pyramids that share corners with three equivalent Ca(1)H6 octahedra, corners with six equivalent Na(1)H6 pentagonal pyramids, edges with three equivalent Ca(1)H6 octahedra, and  a faceface with one Ca(1)H6 octahedra. The corner-sharing octahedral tilt angles are 66°. Ca(1) is bonded to six equivalent H(1) atoms to form CaH6 octahedra that share corners with six equivalent Ca(1)H6 octahedra, corners with three equivalent Na(1)H6 pentagonal pyramids, edges with three equivalent Na(1)H6 pentagonal pyramids, and  a faceface with one Na(1)H6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 44°. H(1) is bonded to two equivalent Na(1) and two equivalent Ca(1) atoms to form a mixture of distorted corner and edge-sharing HNa2Ca2 trigonal pyramids. is represented by the CIF card [CIF]
data_NaCaH3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.112
_cell_length_b   6.112
_cell_length_c   6.112
_cell_angle_alpha   57.392
_cell_angle_beta   57.392
_cell_angle_gamma   57.392
_symmetry_Int_Tables_number   1
_cell_volume   151.745
_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
  Na  Na0  1  0.717  0.717  0.717  1.0
  Na  Na1  1  0.217  0.217  0.217  1.0
  Ca  Ca2  1  0.499  0.499  0.499  1.0
  Ca  Ca3  1  0.999  0.999  0.999  1.0
  H  H4  1  0.807  0.115  0.383  1.0
  H  H5  1  0.115  0.383  0.807  1.0
  H  H6  1  0.383  0.807  0.115  1.0
  H  H7  1  0.307  0.883  0.615  1.0
  H  H8  1  0.883  0.615  0.307  1.0
  H  H9  1  0.615  0.307  0.883  1.0
[/CIF]
.
The structure described by NaCaH3 is Ilmenite-like structured and crystallizes in the trigonal R3c space group. Na(1) is bonded to six equivalent H(1) atoms to form distorted NaH6 pentagonal pyramids that share corners with three equivalent Ca(1)H6 octahedra, corners with six equivalent Na(1)H6 pentagonal pyramids, edges with three equivalent Ca(1)H6 octahedra, and  a faceface with one Ca(1)H6 octahedra. The corner-sharing octahedral tilt angles are 66°. Ca(1) is bonded to six equivalent H(1) atoms to form CaH6 octahedra that share corners with six equivalent Ca(1)H6 octahedra, corners with three equivalent Na(1)H6 pentagonal pyramids, edges with three equivalent Na(1)H6 pentagonal pyramids, and  a faceface with one Na(1)H6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 44°. H(1) is bonded to two equivalent Na(1) and two equivalent Ca(1) atoms to form a mixture of distorted corner and edge-sharing HNa2Ca2 trigonal pyramids. is represented by the CIF card [CIF]
data_NaCaH3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.112
_cell_length_b   6.112
_cell_length_c   6.112
_cell_angle_alpha   57.392
_cell_angle_beta   57.392
_cell_angle_gamma   57.392
_symmetry_Int_Tables_number   1
_cell_volume   151.745
_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
  Na  Na0  1  0.717  0.717  0.717  1.0
  Na  Na1  1  0.217  0.217  0.217  1.0
  Ca  Ca2  1  0.499  0.499  0.499  1.0
  Ca  Ca3  1  0.999  0.999  0.999  1.0
  H  H4  1  0.807  0.115  0.383  1.0
  H  H5  1  0.115  0.383  0.807  1.0
  H  H6  1  0.383  0.807  0.115  1.0
  H  H7  1  0.307  0.883  0.615  1.0
  H  H8  1  0.883  0.615  0.307  1.0
  H  H9  1  0.615  0.307  0.883  1.0
[/CIF]
.