The crystal structure described by MgNb4(O2F)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(4), one O(7), one F(1), and one F(3) atom to form distorted MgO3F2 trigonal bipyramids that share  a cornercorner with one Nb(2)O4F square pyramid,  a cornercorner with one Nb(1)O4F trigonal bipyramid,  a cornercorner with one Nb(3)O4F trigonal bipyramid,  a cornercorner with one Nb(4)O4F trigonal bipyramid,  an edgeedge with one Nb(2)O4F square pyramid, and  an edgeedge with one Nb(4)O4F trigonal bipyramid. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(6), one O(8), and one F(2) atom to form NbO4F trigonal bipyramids that share  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, corners with two equivalent Nb(3)O4F trigonal bipyramids, and corners with two equivalent Nb(4)O4F trigonal bipyramids. In the second Nb site, Nb(2) is bonded to one O(3), one O(4), one O(5), one O(7), and one F(1) atom to form distorted NbO4F square pyramids that share  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, corners with two equivalent Nb(3)O4F trigonal bipyramids, corners with two equivalent Nb(4)O4F trigonal bipyramids, and  an edgeedge with one Mg(1)O3F2 trigonal bipyramid. In the third Nb site, Nb(3) is bonded to one O(2), one O(4), one O(5), one O(6), and one F(4) atom to form distorted NbO4F trigonal bipyramids that share corners with two equivalent Nb(2)O4F square pyramids,  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, and corners with two equivalent Nb(1)O4F trigonal bipyramids. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(3), one O(7), one O(8), and one F(3) atom to form distorted NbO4F trigonal bipyramids that share corners with two equivalent Nb(2)O4F square pyramids,  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, corners with two equivalent Nb(1)O4F trigonal bipyramids, and  an edgeedge with one Mg(1)O3F2 trigonal bipyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Nb(1), and one Nb(4) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(3) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(4) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one Nb(2), and one Nb(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(3) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one Nb(3) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Nb(2), and one Nb(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(4) atom. There are four inequivalent F sites. In the first F site, F(1) is bonded in a bent 120 degrees geometry to one Mg(1) and one Nb(2) atom. In the second F site, F(2) is bonded in a single-bond geometry to one Nb(1) atom. In the third F site, F(3) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Nb(4) atom. In the fourth F site, F(4) is bonded in a single-bond geometry to one Nb(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgNb4(O2F)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.432
_cell_length_b   5.766
_cell_length_c   9.112
_cell_angle_alpha   89.957
_cell_angle_beta   89.190
_cell_angle_gamma   91.331
_symmetry_Int_Tables_number   1
_cell_volume   285.267
_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  0.293  0.863  0.488  1.0
  Nb  Nb1  1  0.123  0.663  0.131  1.0
  Nb  Nb2  1  0.393  0.313  0.637  1.0
  Nb  Nb3  1  0.610  0.824  0.871  1.0
  Nb  Nb4  1  0.869  0.157  0.365  1.0
  O  O5  1  0.084  0.871  0.293  1.0
  O  O6  1  0.877  0.693  0.991  1.0
  O  O7  1  0.621  0.333  0.484  1.0
  O  O8  1  0.445  0.996  0.696  1.0
  O  O9  1  0.530  0.533  0.777  1.0
  O  O10  1  0.371  0.867  0.015  1.0
  O  O11  1  0.112  0.157  0.518  1.0
  O  O12  1  0.946  0.389  0.233  1.0
  F  F13  1  0.166  0.593  0.581  1.0
  F  F14  1  0.389  0.441  0.123  1.0
  F  F15  1  0.598  0.894  0.376  1.0
  F  F16  1  0.849  0.082  0.839  1.0
[/CIF]
.
The crystal structure described by MgNb4(O2F)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(4), one O(7), one F(1), and one F(3) atom to form distorted MgO3F2 trigonal bipyramids that share  a cornercorner with one Nb(2)O4F square pyramid,  a cornercorner with one Nb(1)O4F trigonal bipyramid,  a cornercorner with one Nb(3)O4F trigonal bipyramid,  a cornercorner with one Nb(4)O4F trigonal bipyramid,  an edgeedge with one Nb(2)O4F square pyramid, and  an edgeedge with one Nb(4)O4F trigonal bipyramid. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(6), one O(8), and one F(2) atom to form NbO4F trigonal bipyramids that share  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, corners with two equivalent Nb(3)O4F trigonal bipyramids, and corners with two equivalent Nb(4)O4F trigonal bipyramids. In the second Nb site, Nb(2) is bonded to one O(3), one O(4), one O(5), one O(7), and one F(1) atom to form distorted NbO4F square pyramids that share  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, corners with two equivalent Nb(3)O4F trigonal bipyramids, corners with two equivalent Nb(4)O4F trigonal bipyramids, and  an edgeedge with one Mg(1)O3F2 trigonal bipyramid. In the third Nb site, Nb(3) is bonded to one O(2), one O(4), one O(5), one O(6), and one F(4) atom to form distorted NbO4F trigonal bipyramids that share corners with two equivalent Nb(2)O4F square pyramids,  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, and corners with two equivalent Nb(1)O4F trigonal bipyramids. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(3), one O(7), one O(8), and one F(3) atom to form distorted NbO4F trigonal bipyramids that share corners with two equivalent Nb(2)O4F square pyramids,  a cornercorner with one Mg(1)O3F2 trigonal bipyramid, corners with two equivalent Nb(1)O4F trigonal bipyramids, and  an edgeedge with one Mg(1)O3F2 trigonal bipyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Nb(1), and one Nb(4) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(3) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(4) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one Nb(2), and one Nb(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(3) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one Nb(3) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Nb(2), and one Nb(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(4) atom. There are four inequivalent F sites. In the first F site, F(1) is bonded in a bent 120 degrees geometry to one Mg(1) and one Nb(2) atom. In the second F site, F(2) is bonded in a single-bond geometry to one Nb(1) atom. In the third F site, F(3) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Nb(4) atom. In the fourth F site, F(4) is bonded in a single-bond geometry to one Nb(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgNb4(O2F)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.432
_cell_length_b   5.766
_cell_length_c   9.112
_cell_angle_alpha   89.957
_cell_angle_beta   89.190
_cell_angle_gamma   91.331
_symmetry_Int_Tables_number   1
_cell_volume   285.267
_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  0.293  0.863  0.488  1.0
  Nb  Nb1  1  0.123  0.663  0.131  1.0
  Nb  Nb2  1  0.393  0.313  0.637  1.0
  Nb  Nb3  1  0.610  0.824  0.871  1.0
  Nb  Nb4  1  0.869  0.157  0.365  1.0
  O  O5  1  0.084  0.871  0.293  1.0
  O  O6  1  0.877  0.693  0.991  1.0
  O  O7  1  0.621  0.333  0.484  1.0
  O  O8  1  0.445  0.996  0.696  1.0
  O  O9  1  0.530  0.533  0.777  1.0
  O  O10  1  0.371  0.867  0.015  1.0
  O  O11  1  0.112  0.157  0.518  1.0
  O  O12  1  0.946  0.389  0.233  1.0
  F  F13  1  0.166  0.593  0.581  1.0
  F  F14  1  0.389  0.441  0.123  1.0
  F  F15  1  0.598  0.894  0.376  1.0
  F  F16  1  0.849  0.082  0.839  1.0
[/CIF]
.