The compound described by Mg3Ta6(FeO6)4 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Mg site, Mg(2) is bonded to one O(11), one O(2), one O(5), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share corners with two equivalent Ta(1)O4 tetrahedra, corners with two equivalent Ta(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Ta(2)O5 tetrahedra. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(11), one O(3), and one O(6) atom to form TaO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Ta(2)O5 tetrahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 16-68°. In the second Ta site, Ta(2) is bonded to one O(1), one O(11), one O(4), one O(7), and one O(8) atom to form distorted TaO5 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra,  a cornercorner with one Ta(1)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 41-53°. In the third Ta site, Ta(3) is bonded to one O(12), one O(2), one O(5), and one O(9) atom to form TaO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 19-51°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(6), one O(7), one O(9), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Ta(3)O4 tetrahedra, corners with two equivalent Ta(1)O4 tetrahedra, corners with three equivalent Ta(2)O5 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(12), one O(5), and two equivalent O(8) atoms to form FeO6 octahedra that share  a cornercorner with one Ta(2)O5 tetrahedra, corners with two equivalent Ta(1)O4 tetrahedra, corners with two equivalent Ta(3)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Ta(2)O5 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Ta(2) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Mg(2) and one Ta(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mg(1), one Ta(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ta(2) and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(2), one Ta(3), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(2), one Ta(1), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Mg(2), one Ta(2), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ta(2) and two equivalent Fe(2) atoms. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Ta(3) and one Fe(1) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Fe(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Mg(2), one Ta(1), one Ta(2), and one Fe(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Ta(3) and one Fe(2) atom. is represented by the CIF file [CIF]
data_Mg3Ta6(FeO6)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.038
_cell_length_b   8.261
_cell_length_c   10.245
_cell_angle_alpha   106.252
_cell_angle_beta   103.208
_cell_angle_gamma   102.579
_symmetry_Int_Tables_number   1
_cell_volume   530.828
_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  0.000  0.500  0.500  1.0
  Mg  Mg1  1  0.277  0.278  0.793  1.0
  Mg  Mg2  1  0.723  0.722  0.207  1.0
  Ta  Ta3  1  0.778  0.327  0.727  1.0
  Ta  Ta4  1  0.222  0.673  0.273  1.0
  Ta  Ta5  1  0.895  0.913  0.670  1.0
  Ta  Ta6  1  0.407  0.731  0.879  1.0
  Ta  Ta7  1  0.105  0.087  0.330  1.0
  Ta  Ta8  1  0.593  0.269  0.121  1.0
  Fe  Fe9  1  0.379  0.953  0.608  1.0
  Fe  Fe10  1  0.621  0.047  0.392  1.0
  Fe  Fe11  1  0.044  0.208  0.013  1.0
  Fe  Fe12  1  0.956  0.792  0.987  1.0
  O  O13  1  0.876  0.685  0.581  1.0
  O  O14  1  0.124  0.315  0.419  1.0
  O  O15  1  0.272  0.500  0.758  1.0
  O  O16  1  0.728  0.500  0.242  1.0
  O  O17  1  0.786  0.302  0.538  1.0
  O  O18  1  0.214  0.698  0.462  1.0
  O  O19  1  0.664  0.977  0.578  1.0
  O  O20  1  0.336  0.023  0.422  1.0
  O  O21  1  0.659  0.747  0.011  1.0
  O  O22  1  0.341  0.253  0.989  1.0
  O  O23  1  0.486  0.777  0.273  1.0
  O  O24  1  0.514  0.223  0.727  1.0
  O  O25  1  0.140  0.029  0.647  1.0
  O  O26  1  0.072  0.063  0.137  1.0
  O  O27  1  0.928  0.937  0.863  1.0
  O  O28  1  0.562  0.135  0.238  1.0
  O  O29  1  0.438  0.865  0.762  1.0
  O  O30  1  0.161  0.441  0.166  1.0
  O  O31  1  0.839  0.559  0.834  1.0
  O  O32  1  0.982  0.241  0.818  1.0
  O  O33  1  0.018  0.759  0.182  1.0
  O  O34  1  0.232  0.793  0.980  1.0
  O  O35  1  0.768  0.207  0.020  1.0
  O  O36  1  0.860  0.971  0.353  1.0
[/CIF]
.
The compound described by Mg3Ta6(FeO6)4 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Mg site, Mg(2) is bonded to one O(11), one O(2), one O(5), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share corners with two equivalent Ta(1)O4 tetrahedra, corners with two equivalent Ta(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Ta(2)O5 tetrahedra. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(11), one O(3), and one O(6) atom to form TaO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Ta(2)O5 tetrahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 16-68°. In the second Ta site, Ta(2) is bonded to one O(1), one O(11), one O(4), one O(7), and one O(8) atom to form distorted TaO5 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra,  a cornercorner with one Ta(1)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 41-53°. In the third Ta site, Ta(3) is bonded to one O(12), one O(2), one O(5), and one O(9) atom to form TaO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 19-51°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(6), one O(7), one O(9), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Ta(3)O4 tetrahedra, corners with two equivalent Ta(1)O4 tetrahedra, corners with three equivalent Ta(2)O5 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Fe site, Fe(2) is bonded to one O(10), one O(11), one O(12), one O(5), and two equivalent O(8) atoms to form FeO6 octahedra that share  a cornercorner with one Ta(2)O5 tetrahedra, corners with two equivalent Ta(1)O4 tetrahedra, corners with two equivalent Ta(3)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Ta(2)O5 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Mg(1) and one Ta(2) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Mg(2) and one Ta(3) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Mg(1), one Ta(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ta(2) and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(2), one Ta(3), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(2), one Ta(1), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Mg(2), one Ta(2), and one Fe(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ta(2) and two equivalent Fe(2) atoms. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Ta(3) and one Fe(1) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Fe(2) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Mg(2), one Ta(1), one Ta(2), and one Fe(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Ta(3) and one Fe(2) atom. is represented by the CIF file [CIF]
data_Mg3Ta6(FeO6)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.038
_cell_length_b   8.261
_cell_length_c   10.245
_cell_angle_alpha   106.252
_cell_angle_beta   103.208
_cell_angle_gamma   102.579
_symmetry_Int_Tables_number   1
_cell_volume   530.828
_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  0.000  0.500  0.500  1.0
  Mg  Mg1  1  0.277  0.278  0.793  1.0
  Mg  Mg2  1  0.723  0.722  0.207  1.0
  Ta  Ta3  1  0.778  0.327  0.727  1.0
  Ta  Ta4  1  0.222  0.673  0.273  1.0
  Ta  Ta5  1  0.895  0.913  0.670  1.0
  Ta  Ta6  1  0.407  0.731  0.879  1.0
  Ta  Ta7  1  0.105  0.087  0.330  1.0
  Ta  Ta8  1  0.593  0.269  0.121  1.0
  Fe  Fe9  1  0.379  0.953  0.608  1.0
  Fe  Fe10  1  0.621  0.047  0.392  1.0
  Fe  Fe11  1  0.044  0.208  0.013  1.0
  Fe  Fe12  1  0.956  0.792  0.987  1.0
  O  O13  1  0.876  0.685  0.581  1.0
  O  O14  1  0.124  0.315  0.419  1.0
  O  O15  1  0.272  0.500  0.758  1.0
  O  O16  1  0.728  0.500  0.242  1.0
  O  O17  1  0.786  0.302  0.538  1.0
  O  O18  1  0.214  0.698  0.462  1.0
  O  O19  1  0.664  0.977  0.578  1.0
  O  O20  1  0.336  0.023  0.422  1.0
  O  O21  1  0.659  0.747  0.011  1.0
  O  O22  1  0.341  0.253  0.989  1.0
  O  O23  1  0.486  0.777  0.273  1.0
  O  O24  1  0.514  0.223  0.727  1.0
  O  O25  1  0.140  0.029  0.647  1.0
  O  O26  1  0.072  0.063  0.137  1.0
  O  O27  1  0.928  0.937  0.863  1.0
  O  O28  1  0.562  0.135  0.238  1.0
  O  O29  1  0.438  0.865  0.762  1.0
  O  O30  1  0.161  0.441  0.166  1.0
  O  O31  1  0.839  0.559  0.834  1.0
  O  O32  1  0.982  0.241  0.818  1.0
  O  O33  1  0.018  0.759  0.182  1.0
  O  O34  1  0.232  0.793  0.980  1.0
  O  O35  1  0.768  0.207  0.020  1.0
  O  O36  1  0.860  0.971  0.353  1.0
[/CIF]
.