The crystal structure described by ErBH4 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent H(2), four equivalent H(3), and four equivalent H(4) atoms. In the second Er site, Er(2) is bonded to one H(4), two equivalent H(1), two equivalent H(2), three equivalent H(5), and four equivalent H(3) atoms to form ErH12 cuboctahedra that share edges with seven equivalent Er(2)H12 cuboctahedra, edges with two equivalent B(1)H4 tetrahedra, and edges with four equivalent B(2)H4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to two equivalent H(1) and two equivalent H(2) atoms to form BH4 tetrahedra that share edges with four equivalent Er(2)H12 cuboctahedra. In the second B site, B(2) is bonded to one H(4), one H(5), and two equivalent H(3) atoms to form BH4 tetrahedra that share edges with four equivalent Er(2)H12 cuboctahedra. There are five inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one Er(1), two equivalent Er(2), and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Er(1), two equivalent Er(2), and one B(1) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Er(1), two equivalent Er(2), and one B(2) atom. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one Er(2), two equivalent Er(1), and one B(2) atom. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to three equivalent Er(2) and one B(2) atom. is represented by the CIF file [CIF]
data_ErBH4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.018
_cell_length_b   5.625
_cell_length_c   6.845
_cell_angle_alpha   114.260
_cell_angle_beta   107.068
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   133.561
_cell_formula_units_Z   3
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
  Er  Er0  1  0.000  0.544  1.000  1.0
  Er  Er1  1  0.336  0.889  0.672  1.0
  Er  Er2  1  0.664  0.217  0.328  1.0
  B  B3  1  1.000  0.055  0.000  1.0
  B  B4  1  0.334  0.386  0.669  1.0
  B  B5  1  0.665  0.717  0.331  1.0
  H  H6  1  0.908  0.094  0.817  1.0
  H  H7  1  0.092  0.277  0.183  1.0
  H  H8  1  0.745  0.918  0.000  1.0
  H  H9  1  0.255  0.918  1.000  1.0
  H  H10  1  0.080  0.518  0.673  1.0
  H  H11  1  0.920  0.846  0.327  1.0
  H  H12  1  0.420  0.334  0.840  1.0
  H  H13  1  0.580  0.494  0.160  1.0
  H  H14  1  0.593  0.518  0.673  1.0
  H  H15  1  0.407  0.846  0.327  1.0
  H  H16  1  0.242  0.176  0.483  1.0
  H  H17  1  0.758  0.693  0.517  1.0
[/CIF]
.
The crystal structure described by ErBH4 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 12-coordinate geometry to two equivalent H(1), two equivalent H(2), four equivalent H(3), and four equivalent H(4) atoms. In the second Er site, Er(2) is bonded to one H(4), two equivalent H(1), two equivalent H(2), three equivalent H(5), and four equivalent H(3) atoms to form ErH12 cuboctahedra that share edges with seven equivalent Er(2)H12 cuboctahedra, edges with two equivalent B(1)H4 tetrahedra, and edges with four equivalent B(2)H4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to two equivalent H(1) and two equivalent H(2) atoms to form BH4 tetrahedra that share edges with four equivalent Er(2)H12 cuboctahedra. In the second B site, B(2) is bonded to one H(4), one H(5), and two equivalent H(3) atoms to form BH4 tetrahedra that share edges with four equivalent Er(2)H12 cuboctahedra. There are five inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one Er(1), two equivalent Er(2), and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Er(1), two equivalent Er(2), and one B(1) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one Er(1), two equivalent Er(2), and one B(2) atom. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one Er(2), two equivalent Er(1), and one B(2) atom. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to three equivalent Er(2) and one B(2) atom. is represented by the CIF file [CIF]
data_ErBH4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.018
_cell_length_b   5.625
_cell_length_c   6.845
_cell_angle_alpha   114.260
_cell_angle_beta   107.068
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   133.561
_cell_formula_units_Z   3
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
  Er  Er0  1  0.000  0.544  1.000  1.0
  Er  Er1  1  0.336  0.889  0.672  1.0
  Er  Er2  1  0.664  0.217  0.328  1.0
  B  B3  1  1.000  0.055  0.000  1.0
  B  B4  1  0.334  0.386  0.669  1.0
  B  B5  1  0.665  0.717  0.331  1.0
  H  H6  1  0.908  0.094  0.817  1.0
  H  H7  1  0.092  0.277  0.183  1.0
  H  H8  1  0.745  0.918  0.000  1.0
  H  H9  1  0.255  0.918  1.000  1.0
  H  H10  1  0.080  0.518  0.673  1.0
  H  H11  1  0.920  0.846  0.327  1.0
  H  H12  1  0.420  0.334  0.840  1.0
  H  H13  1  0.580  0.494  0.160  1.0
  H  H14  1  0.593  0.518  0.673  1.0
  H  H15  1  0.407  0.846  0.327  1.0
  H  H16  1  0.242  0.176  0.483  1.0
  H  H17  1  0.758  0.693  0.517  1.0
[/CIF]
.