data_MgFeAs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.6
_cell_length_b   3.6
_cell_length_c   6.6
_cell_angle_alpha   105.0
_cell_angle_beta   105.0
_cell_angle_gamma   58.29
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgFeAs2
_chemical_formula_sum   'Mg1 Fe1 As2'
_cell_volume   69.54
_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  Mg3  1  0.0  0.0  0.0  1.0
  Fe  Fe2  1  0.17  0.0  0.15  1.0
  As  As0  1  0.1  0.0  0.44  1.0
  As  As1  1  0.23  0.0  0.86  1.0

data_MgFeAs2
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.51
_cell_length_b   3.6
_cell_length_c   6.6
_cell_angle_alpha   105.0
_cell_angle_beta   90.0
_cell_angle_gamma   119.14
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgFeAs2
_chemical_formula_sum   'Mg1 Fe1 As2'
_cell_volume   69.54
_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  Mg0  1  0.0  0.0  0.0  1.0
  Fe  Fe1  1  0.0  0.83  0.85  1.0
  As  As2  1  0.0  0.77  0.14  1.0
  As  As3  1  0.0  0.9  0.56  1.0

Mg Fe As As
Mg Fe As As 0 1 o o o 0 3 o o - 1 2 o o o 
MgFeAs2 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one MgFeAs2 cluster. Mg(1) is bonded in a distorted water-like geometry to one Fe(1) and one As(2) atom. The Mg(1)-Fe(1) bond length is 1.03 Å. The Mg(1)-As(2) bond length is 1.39 Å. Fe(1) is bonded in a distorted single-bond geometry to one Mg(1) and one As(1) atom. The Fe(1)-As(1) bond length is 2.00 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded in a single-bond geometry to one Fe(1) atom. In the second As site, As(2) is bonded in a distorted single-bond geometry to one Mg(1) atom.