data_MgBeNb2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.66
_cell_length_b   9.66
_cell_length_c   9.66
_cell_angle_alpha   17.04
_cell_angle_beta   17.04
_cell_angle_gamma   17.04
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgBeNb2
_chemical_formula_sum   'Mg1 Be1 Nb2'
_cell_volume   67.5
_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  Mg1  1  0.0  0.0  0.28  1.0
  Be  Be0  1  0.0  0.0  0.0  1.0
  Nb  Nb2  1  0.0  0.0  0.39  1.0
  Nb  Nb3  1  0.0  0.0  0.16  1.0

data_MgBeNb2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.96
_cell_length_b   2.86
_cell_length_c   9.66
_cell_angle_alpha   90.0
_cell_angle_beta   99.85
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgBeNb2
_chemical_formula_sum   'Mg2 Be2 Nb4'
_cell_volume   135.0
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  2  0.0  0.0  0.72  1.0
  Be  Be1  2  0.0  0.0  0.0  1.0
  Nb  Nb2  2  0.0  0.0  0.61  1.0
  Nb  Nb3  2  0.0  0.0  0.84  1.0

Mg Be Nb Nb
Mg Be Nb Nb 0 3 o o o 0 2 o o o 1 3 o o o 
MgBeNb2 is Cyanogen Chloride-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two MgBeNb2 clusters. Mg(1) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. The Mg(1)-Nb(1) bond length is 1.08 Å. The Mg(1)-Nb(2) bond length is 1.08 Å. Be(1) is bonded in a single-bond geometry to one Nb(2) atom. The Be(1)-Nb(2) bond length is 1.59 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a single-bond geometry to one Mg(1) atom. In the second Nb site, Nb(2) is bonded in a distorted single-bond geometry to one Mg(1) and one Be(1) atom.