The structure described by (NH4)2Cr2O7 is Silicon tetrafluoride-derived structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of eight ammonium molecules and four Cr2O7 clusters. In each Cr2O7 cluster, Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Cr(1) atoms. In the second O site, O(2) is bonded in a single-bond geometry to one Cr(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Cr(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Cr(1) atom. is represented by the CIF file [CIF]
data_Cr2H8N2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.734
_cell_length_b   7.734
_cell_length_c   7.832
_cell_angle_alpha   87.191
_cell_angle_beta   87.191
_cell_angle_gamma   58.926
_symmetry_Int_Tables_number   1
_cell_volume   400.585
_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
  Cr  Cr0  1  0.769  0.432  0.640  1.0
  Cr  Cr1  1  0.568  0.231  0.860  1.0
  Cr  Cr2  1  0.231  0.568  0.360  1.0
  Cr  Cr3  1  0.432  0.769  0.140  1.0
  H  H4  1  0.905  0.299  0.267  1.0
  H  H5  1  0.701  0.095  0.233  1.0
  H  H6  1  0.095  0.701  0.733  1.0
  H  H7  1  0.299  0.905  0.767  1.0
  H  H8  1  0.001  0.426  0.160  1.0
  H  H9  1  0.574  0.999  0.340  1.0
  H  H10  1  0.999  0.574  0.840  1.0
  H  H11  1  0.426  0.001  0.660  1.0
  H  H12  1  0.921  0.298  0.048  1.0
  H  H13  1  0.702  0.079  0.452  1.0
  H  H14  1  0.079  0.702  0.952  1.0
  H  H15  1  0.298  0.921  0.548  1.0
  H  H16  1  0.130  0.169  0.166  1.0
  H  H17  1  0.831  0.870  0.334  1.0
  H  H18  1  0.870  0.831  0.834  1.0
  H  H19  1  0.169  0.130  0.666  1.0
  N  N20  1  0.988  0.299  0.158  1.0
  N  N21  1  0.701  0.012  0.342  1.0
  N  N22  1  0.012  0.701  0.842  1.0
  N  N23  1  0.299  0.988  0.658  1.0
  O  O24  1  0.552  0.448  0.750  1.0
  O  O25  1  0.448  0.552  0.250  1.0
  O  O26  1  0.857  0.255  0.498  1.0
  O  O27  1  0.745  0.143  0.002  1.0
  O  O28  1  0.143  0.745  0.502  1.0
  O  O29  1  0.255  0.857  0.998  1.0
  O  O30  1  0.948  0.369  0.779  1.0
  O  O31  1  0.631  0.052  0.721  1.0
  O  O32  1  0.052  0.631  0.221  1.0
  O  O33  1  0.369  0.948  0.279  1.0
  O  O34  1  0.706  0.648  0.549  1.0
  O  O35  1  0.352  0.294  0.951  1.0
  O  O36  1  0.294  0.352  0.451  1.0
  O  O37  1  0.648  0.706  0.049  1.0
[/CIF]
.
The structure described by (NH4)2Cr2O7 is Silicon tetrafluoride-derived structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of eight ammonium molecules and four Cr2O7 clusters. In each Cr2O7 cluster, Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Cr(1) atoms. In the second O site, O(2) is bonded in a single-bond geometry to one Cr(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to one Cr(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Cr(1) atom. is represented by the CIF file [CIF]
data_Cr2H8N2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.734
_cell_length_b   7.734
_cell_length_c   7.832
_cell_angle_alpha   87.191
_cell_angle_beta   87.191
_cell_angle_gamma   58.926
_symmetry_Int_Tables_number   1
_cell_volume   400.585
_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
  Cr  Cr0  1  0.769  0.432  0.640  1.0
  Cr  Cr1  1  0.568  0.231  0.860  1.0
  Cr  Cr2  1  0.231  0.568  0.360  1.0
  Cr  Cr3  1  0.432  0.769  0.140  1.0
  H  H4  1  0.905  0.299  0.267  1.0
  H  H5  1  0.701  0.095  0.233  1.0
  H  H6  1  0.095  0.701  0.733  1.0
  H  H7  1  0.299  0.905  0.767  1.0
  H  H8  1  0.001  0.426  0.160  1.0
  H  H9  1  0.574  0.999  0.340  1.0
  H  H10  1  0.999  0.574  0.840  1.0
  H  H11  1  0.426  0.001  0.660  1.0
  H  H12  1  0.921  0.298  0.048  1.0
  H  H13  1  0.702  0.079  0.452  1.0
  H  H14  1  0.079  0.702  0.952  1.0
  H  H15  1  0.298  0.921  0.548  1.0
  H  H16  1  0.130  0.169  0.166  1.0
  H  H17  1  0.831  0.870  0.334  1.0
  H  H18  1  0.870  0.831  0.834  1.0
  H  H19  1  0.169  0.130  0.666  1.0
  N  N20  1  0.988  0.299  0.158  1.0
  N  N21  1  0.701  0.012  0.342  1.0
  N  N22  1  0.012  0.701  0.842  1.0
  N  N23  1  0.299  0.988  0.658  1.0
  O  O24  1  0.552  0.448  0.750  1.0
  O  O25  1  0.448  0.552  0.250  1.0
  O  O26  1  0.857  0.255  0.498  1.0
  O  O27  1  0.745  0.143  0.002  1.0
  O  O28  1  0.143  0.745  0.502  1.0
  O  O29  1  0.255  0.857  0.998  1.0
  O  O30  1  0.948  0.369  0.779  1.0
  O  O31  1  0.631  0.052  0.721  1.0
  O  O32  1  0.052  0.631  0.221  1.0
  O  O33  1  0.369  0.948  0.279  1.0
  O  O34  1  0.706  0.648  0.549  1.0
  O  O35  1  0.352  0.294  0.951  1.0
  O  O36  1  0.294  0.352  0.451  1.0
  O  O37  1  0.648  0.706  0.049  1.0
[/CIF]
.