The crystal structure described by MgFe4As2O11 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(11), one O(3), and one O(7) atom to form MgO4 trigonal pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, and corners with two equivalent As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-89°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(2), one O(3), and one O(5) atom. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles are 27°. In the third Fe site, Fe(3) is bonded to one O(1), one O(10), one O(11), one O(2), one O(5), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles are 27°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(11), one O(5), one O(7), and one O(9) atom to form AsO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, and corners with two equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 43-60°. In the second As site, As(2) is bonded to one O(10), one O(4), one O(6), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(1), one Fe(2), one Fe(3), and one Fe(4) atom to form distorted edge-sharing OMgFe4 trigonal bipyramids. In the second O site, O(2) is bonded to one Fe(1), one Fe(2), one Fe(3), and one Fe(4) atom to form distorted edge-sharing OFe4 tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(1), and one Fe(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(2), one Fe(4), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Fe(4) and one As(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(4), and one As(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one As(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(4), and one As(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1), one Fe(3), and one As(2) atom. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Mg(1), one Fe(3), and one As(1) atom. is represented by the CIF file [CIF]
data_MgFe4As2O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.343
_cell_length_b   6.531
_cell_length_c   6.934
_cell_angle_alpha   109.248
_cell_angle_beta   103.421
_cell_angle_gamma   98.629
_symmetry_Int_Tables_number   1
_cell_volume   215.346
_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  0.814  0.658  0.742  1.0
  Fe  Fe1  1  0.156  0.792  0.111  1.0
  Fe  Fe2  1  0.898  0.238  0.957  1.0
  Fe  Fe3  1  0.636  0.599  0.218  1.0
  Fe  Fe4  1  0.329  0.354  0.747  1.0
  As  As5  1  0.315  0.813  0.600  1.0
  As  As6  1  0.683  0.175  0.391  1.0
  O  O7  1  0.747  0.522  0.954  1.0
  O  O8  1  0.257  0.470  0.052  1.0
  O  O9  1  0.972  0.970  0.960  1.0
  O  O10  1  0.919  0.212  0.625  1.0
  O  O11  1  0.061  0.798  0.388  1.0
  O  O12  1  0.425  0.269  0.460  1.0
  O  O13  1  0.187  0.644  0.717  1.0
  O  O14  1  0.791  0.336  0.252  1.0
  O  O15  1  0.470  0.079  0.784  1.0
  O  O16  1  0.573  0.901  0.209  1.0
  O  O17  1  0.569  0.709  0.513  1.0
[/CIF]
.
The crystal structure described by MgFe4As2O11 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(11), one O(3), and one O(7) atom to form MgO4 trigonal pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, and corners with two equivalent As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-89°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(2), one O(3), and one O(5) atom. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles are 27°. In the third Fe site, Fe(3) is bonded to one O(1), one O(10), one O(11), one O(2), one O(5), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles are 27°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra, corners with two equivalent Mg(1)O4 trigonal pyramids,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(11), one O(5), one O(7), and one O(9) atom to form AsO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, and corners with two equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 43-60°. In the second As site, As(2) is bonded to one O(10), one O(4), one O(6), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(1), one Fe(2), one Fe(3), and one Fe(4) atom to form distorted edge-sharing OMgFe4 trigonal bipyramids. In the second O site, O(2) is bonded to one Fe(1), one Fe(2), one Fe(3), and one Fe(4) atom to form distorted edge-sharing OFe4 tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(1), and one Fe(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(2), one Fe(4), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(3), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Fe(4) and one As(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(4), and one As(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(3), and one As(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Fe(2), one Fe(4), and one As(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1), one Fe(3), and one As(2) atom. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Mg(1), one Fe(3), and one As(1) atom. is represented by the CIF file [CIF]
data_MgFe4As2O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.343
_cell_length_b   6.531
_cell_length_c   6.934
_cell_angle_alpha   109.248
_cell_angle_beta   103.421
_cell_angle_gamma   98.629
_symmetry_Int_Tables_number   1
_cell_volume   215.346
_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  0.814  0.658  0.742  1.0
  Fe  Fe1  1  0.156  0.792  0.111  1.0
  Fe  Fe2  1  0.898  0.238  0.957  1.0
  Fe  Fe3  1  0.636  0.599  0.218  1.0
  Fe  Fe4  1  0.329  0.354  0.747  1.0
  As  As5  1  0.315  0.813  0.600  1.0
  As  As6  1  0.683  0.175  0.391  1.0
  O  O7  1  0.747  0.522  0.954  1.0
  O  O8  1  0.257  0.470  0.052  1.0
  O  O9  1  0.972  0.970  0.960  1.0
  O  O10  1  0.919  0.212  0.625  1.0
  O  O11  1  0.061  0.798  0.388  1.0
  O  O12  1  0.425  0.269  0.460  1.0
  O  O13  1  0.187  0.644  0.717  1.0
  O  O14  1  0.791  0.336  0.252  1.0
  O  O15  1  0.470  0.079  0.784  1.0
  O  O16  1  0.573  0.901  0.209  1.0
  O  O17  1  0.569  0.709  0.513  1.0
[/CIF]
.