The material structure described by V4O9 crystallizes in the orthorhombic Pnma space group. There are four inequivalent V sites. In the first V site, V(1) is bonded in a 6-coordinate geometry to one O(3), one O(5), one O(7), and three equivalent O(1) atoms. In the second V site, V(2) is bonded to one O(1), one O(3), one O(6), one O(8), and two equivalent O(7) atoms to form distorted VO6 octahedra that share corners with two equivalent V(2)O6 octahedra and  a cornercorner with one V(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 31°. In the third V site, V(3) is bonded to one O(2), one O(4), one O(6), and two equivalent O(9) atoms to form distorted VO5 trigonal bipyramids that share  a cornercorner with one V(2)O6 octahedra and corners with two equivalent V(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 9°. In the fourth V site, V(4) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(8), one O(9), and two equivalent O(2) atoms. There are nine inequivalent O sites. In the first O site, O(5) is bonded in a single-bond geometry to one V(1) atom. In the second O site, O(6) is bonded in a linear geometry to one V(2) and one V(3) atom. In the third O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one V(1) and two equivalent V(2) atoms. In the fourth O site, O(8) is bonded in a single-bond geometry to one V(2) and one V(4) atom. In the fifth O site, O(1) is bonded in a 4-coordinate geometry to one V(2) and three equivalent V(1) atoms. In the sixth O site, O(9) is bonded in a distorted T-shaped geometry to one V(4) and two equivalent V(3) atoms. In the seventh O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one V(3) and two equivalent V(4) atoms. In the eighth O site, O(3) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one V(4) atom. In the ninth O site, O(4) is bonded in a linear geometry to one V(3) and one V(4) atom. is represented by the CIF card [CIF]
data_V4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.704
_cell_length_b   9.555
_cell_length_c   18.196
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   643.934
_cell_formula_units_Z   4
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
  V  V0  1  0.750  0.036  0.422  1.0
  V  V1  1  0.250  0.964  0.578  1.0
  V  V2  1  0.750  0.464  0.922  1.0
  V  V3  1  0.250  0.536  0.078  1.0
  V  V4  1  0.250  0.270  0.490  1.0
  V  V5  1  0.750  0.770  0.010  1.0
  V  V6  1  0.250  0.230  0.990  1.0
  V  V7  1  0.750  0.730  0.510  1.0
  V  V8  1  0.250  0.454  0.317  1.0
  V  V9  1  0.250  0.046  0.817  1.0
  V  V10  1  0.750  0.954  0.183  1.0
  V  V11  1  0.750  0.546  0.683  1.0
  V  V12  1  0.250  0.203  0.168  1.0
  V  V13  1  0.250  0.297  0.668  1.0
  V  V14  1  0.750  0.797  0.832  1.0
  V  V15  1  0.750  0.703  0.332  1.0
  O  O16  1  0.250  0.448  0.951  1.0
  O  O17  1  0.250  0.052  0.451  1.0
  O  O18  1  0.750  0.552  0.049  1.0
  O  O19  1  0.750  0.948  0.549  1.0
  O  O20  1  0.250  0.649  0.345  1.0
  O  O21  1  0.750  0.351  0.655  1.0
  O  O22  1  0.250  0.851  0.845  1.0
  O  O23  1  0.750  0.149  0.155  1.0
  O  O24  1  0.250  0.156  0.585  1.0
  O  O25  1  0.250  0.344  0.085  1.0
  O  O26  1  0.750  0.844  0.415  1.0
  O  O27  1  0.750  0.656  0.915  1.0
  O  O28  1  0.750  0.817  0.260  1.0
  O  O29  1  0.250  0.317  0.240  1.0
  O  O30  1  0.250  0.183  0.740  1.0
  O  O31  1  0.750  0.683  0.760  1.0
  O  O32  1  0.250  0.583  0.163  1.0
  O  O33  1  0.750  0.417  0.837  1.0
  O  O34  1  0.250  0.917  0.663  1.0
  O  O35  1  0.750  0.083  0.337  1.0
  O  O36  1  0.250  0.353  0.396  1.0
  O  O37  1  0.750  0.853  0.104  1.0
  O  O38  1  0.250  0.147  0.896  1.0
  O  O39  1  0.750  0.647  0.604  1.0
  O  O40  1  0.250  0.722  0.023  1.0
  O  O41  1  0.750  0.278  0.977  1.0
  O  O42  1  0.250  0.778  0.523  1.0
  O  O43  1  0.750  0.222  0.477  1.0
  O  O44  1  0.750  0.907  0.955  1.0
  O  O45  1  0.750  0.593  0.455  1.0
  O  O46  1  0.250  0.407  0.545  1.0
  O  O47  1  0.250  0.093  0.045  1.0
  O  O48  1  0.750  0.509  0.298  1.0
  O  O49  1  0.750  0.991  0.798  1.0
  O  O50  1  0.250  0.009  0.202  1.0
  O  O51  1  0.250  0.491  0.702  1.0
[/CIF]
.
The material structure described by V4O9 crystallizes in the orthorhombic Pnma space group. There are four inequivalent V sites. In the first V site, V(1) is bonded in a 6-coordinate geometry to one O(3), one O(5), one O(7), and three equivalent O(1) atoms. In the second V site, V(2) is bonded to one O(1), one O(3), one O(6), one O(8), and two equivalent O(7) atoms to form distorted VO6 octahedra that share corners with two equivalent V(2)O6 octahedra and  a cornercorner with one V(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 31°. In the third V site, V(3) is bonded to one O(2), one O(4), one O(6), and two equivalent O(9) atoms to form distorted VO5 trigonal bipyramids that share  a cornercorner with one V(2)O6 octahedra and corners with two equivalent V(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 9°. In the fourth V site, V(4) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(8), one O(9), and two equivalent O(2) atoms. There are nine inequivalent O sites. In the first O site, O(5) is bonded in a single-bond geometry to one V(1) atom. In the second O site, O(6) is bonded in a linear geometry to one V(2) and one V(3) atom. In the third O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one V(1) and two equivalent V(2) atoms. In the fourth O site, O(8) is bonded in a single-bond geometry to one V(2) and one V(4) atom. In the fifth O site, O(1) is bonded in a 4-coordinate geometry to one V(2) and three equivalent V(1) atoms. In the sixth O site, O(9) is bonded in a distorted T-shaped geometry to one V(4) and two equivalent V(3) atoms. In the seventh O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one V(3) and two equivalent V(4) atoms. In the eighth O site, O(3) is bonded in a distorted trigonal planar geometry to one V(1), one V(2), and one V(4) atom. In the ninth O site, O(4) is bonded in a linear geometry to one V(3) and one V(4) atom. is represented by the CIF card [CIF]
data_V4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.704
_cell_length_b   9.555
_cell_length_c   18.196
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   643.934
_cell_formula_units_Z   4
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
  V  V0  1  0.750  0.036  0.422  1.0
  V  V1  1  0.250  0.964  0.578  1.0
  V  V2  1  0.750  0.464  0.922  1.0
  V  V3  1  0.250  0.536  0.078  1.0
  V  V4  1  0.250  0.270  0.490  1.0
  V  V5  1  0.750  0.770  0.010  1.0
  V  V6  1  0.250  0.230  0.990  1.0
  V  V7  1  0.750  0.730  0.510  1.0
  V  V8  1  0.250  0.454  0.317  1.0
  V  V9  1  0.250  0.046  0.817  1.0
  V  V10  1  0.750  0.954  0.183  1.0
  V  V11  1  0.750  0.546  0.683  1.0
  V  V12  1  0.250  0.203  0.168  1.0
  V  V13  1  0.250  0.297  0.668  1.0
  V  V14  1  0.750  0.797  0.832  1.0
  V  V15  1  0.750  0.703  0.332  1.0
  O  O16  1  0.250  0.448  0.951  1.0
  O  O17  1  0.250  0.052  0.451  1.0
  O  O18  1  0.750  0.552  0.049  1.0
  O  O19  1  0.750  0.948  0.549  1.0
  O  O20  1  0.250  0.649  0.345  1.0
  O  O21  1  0.750  0.351  0.655  1.0
  O  O22  1  0.250  0.851  0.845  1.0
  O  O23  1  0.750  0.149  0.155  1.0
  O  O24  1  0.250  0.156  0.585  1.0
  O  O25  1  0.250  0.344  0.085  1.0
  O  O26  1  0.750  0.844  0.415  1.0
  O  O27  1  0.750  0.656  0.915  1.0
  O  O28  1  0.750  0.817  0.260  1.0
  O  O29  1  0.250  0.317  0.240  1.0
  O  O30  1  0.250  0.183  0.740  1.0
  O  O31  1  0.750  0.683  0.760  1.0
  O  O32  1  0.250  0.583  0.163  1.0
  O  O33  1  0.750  0.417  0.837  1.0
  O  O34  1  0.250  0.917  0.663  1.0
  O  O35  1  0.750  0.083  0.337  1.0
  O  O36  1  0.250  0.353  0.396  1.0
  O  O37  1  0.750  0.853  0.104  1.0
  O  O38  1  0.250  0.147  0.896  1.0
  O  O39  1  0.750  0.647  0.604  1.0
  O  O40  1  0.250  0.722  0.023  1.0
  O  O41  1  0.750  0.278  0.977  1.0
  O  O42  1  0.250  0.778  0.523  1.0
  O  O43  1  0.750  0.222  0.477  1.0
  O  O44  1  0.750  0.907  0.955  1.0
  O  O45  1  0.750  0.593  0.455  1.0
  O  O46  1  0.250  0.407  0.545  1.0
  O  O47  1  0.250  0.093  0.045  1.0
  O  O48  1  0.750  0.509  0.298  1.0
  O  O49  1  0.750  0.991  0.798  1.0
  O  O50  1  0.250  0.009  0.202  1.0
  O  O51  1  0.250  0.491  0.702  1.0
[/CIF]
.