The material described by MgV4O9 crystallizes in the tetragonal P4/n space group. Mg(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. V(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), and three equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent V(1) atoms to form a mixture of distorted corner and edge-sharing OV4 trigonal pyramids. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Mg(1) and one V(1) atom. In the third O site, O(3) is bonded to one Mg(1) and three equivalent V(1) atoms to form distorted OMgV3 tetrahedra that share corners with three equivalent O(3)MgV3 tetrahedra,  a cornercorner with one O(1)V4 trigonal pyramid, edges with three equivalent O(3)MgV3 tetrahedra, and  an edgeedge with one O(1)V4 trigonal pyramid. is represented by the CIF file [CIF]
data_MgV4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.998
_cell_length_b   8.295
_cell_length_c   8.295
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   343.907
_cell_formula_units_Z   2
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  0.160  0.250  0.250  1.0
  Mg  Mg1  1  0.840  0.750  0.750  1.0
  V  V2  1  0.631  0.532  0.340  1.0
  V  V3  1  0.369  0.840  0.468  1.0
  V  V4  1  0.631  0.340  0.968  1.0
  V  V5  1  0.369  0.032  0.840  1.0
  V  V6  1  0.631  0.968  0.160  1.0
  V  V7  1  0.631  0.160  0.532  1.0
  V  V8  1  0.369  0.468  0.660  1.0
  V  V9  1  0.369  0.660  0.032  1.0
  O  O10  1  0.500  0.750  0.250  1.0
  O  O11  1  0.500  0.250  0.750  1.0
  O  O12  1  0.052  0.685  0.980  1.0
  O  O13  1  0.052  0.520  0.685  1.0
  O  O14  1  0.052  0.980  0.815  1.0
  O  O15  1  0.052  0.815  0.520  1.0
  O  O16  1  0.948  0.315  0.020  1.0
  O  O17  1  0.948  0.480  0.315  1.0
  O  O18  1  0.948  0.020  0.185  1.0
  O  O19  1  0.948  0.185  0.480  1.0
  O  O20  1  0.447  0.047  0.356  1.0
  O  O21  1  0.447  0.144  0.047  1.0
  O  O22  1  0.447  0.356  0.453  1.0
  O  O23  1  0.447  0.453  0.144  1.0
  O  O24  1  0.553  0.547  0.856  1.0
  O  O25  1  0.553  0.856  0.953  1.0
  O  O26  1  0.553  0.644  0.547  1.0
  O  O27  1  0.553  0.953  0.644  1.0
[/CIF]
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The material described by MgV4O9 crystallizes in the tetragonal P4/n space group. Mg(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. V(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), and three equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent V(1) atoms to form a mixture of distorted corner and edge-sharing OV4 trigonal pyramids. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Mg(1) and one V(1) atom. In the third O site, O(3) is bonded to one Mg(1) and three equivalent V(1) atoms to form distorted OMgV3 tetrahedra that share corners with three equivalent O(3)MgV3 tetrahedra,  a cornercorner with one O(1)V4 trigonal pyramid, edges with three equivalent O(3)MgV3 tetrahedra, and  an edgeedge with one O(1)V4 trigonal pyramid. is represented by the CIF file [CIF]
data_MgV4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.998
_cell_length_b   8.295
_cell_length_c   8.295
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   343.907
_cell_formula_units_Z   2
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  0.160  0.250  0.250  1.0
  Mg  Mg1  1  0.840  0.750  0.750  1.0
  V  V2  1  0.631  0.532  0.340  1.0
  V  V3  1  0.369  0.840  0.468  1.0
  V  V4  1  0.631  0.340  0.968  1.0
  V  V5  1  0.369  0.032  0.840  1.0
  V  V6  1  0.631  0.968  0.160  1.0
  V  V7  1  0.631  0.160  0.532  1.0
  V  V8  1  0.369  0.468  0.660  1.0
  V  V9  1  0.369  0.660  0.032  1.0
  O  O10  1  0.500  0.750  0.250  1.0
  O  O11  1  0.500  0.250  0.750  1.0
  O  O12  1  0.052  0.685  0.980  1.0
  O  O13  1  0.052  0.520  0.685  1.0
  O  O14  1  0.052  0.980  0.815  1.0
  O  O15  1  0.052  0.815  0.520  1.0
  O  O16  1  0.948  0.315  0.020  1.0
  O  O17  1  0.948  0.480  0.315  1.0
  O  O18  1  0.948  0.020  0.185  1.0
  O  O19  1  0.948  0.185  0.480  1.0
  O  O20  1  0.447  0.047  0.356  1.0
  O  O21  1  0.447  0.144  0.047  1.0
  O  O22  1  0.447  0.356  0.453  1.0
  O  O23  1  0.447  0.453  0.144  1.0
  O  O24  1  0.553  0.547  0.856  1.0
  O  O25  1  0.553  0.856  0.953  1.0
  O  O26  1  0.553  0.644  0.547  1.0
  O  O27  1  0.553  0.953  0.644  1.0
[/CIF]
.