The material described by Rb2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(10), one O(3), one O(4), one O(5), one O(6), one O(9), and two equivalent O(7) atoms. In the second Rb site, Rb(2) is bonded in a 9-coordinate geometry to one O(1), one O(12), one O(13), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(9) atom. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(2), one O(5), one O(6), and two equivalent O(14) atoms. In the fourth Rb site, Rb(4) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(2), one O(3), one O(8), and one O(9) atom. There are four inequivalent Cr sites. In the first Cr site, 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. In the second Cr site, Cr(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form corner-sharing CrO4 tetrahedra. In the third Cr site, Cr(3) is bonded to one O(10), one O(11), one O(8), and one O(9) atom to form corner-sharing CrO4 tetrahedra. In the fourth Cr site, Cr(4) is bonded to one O(12), one O(13), one O(14), and one O(8) atom to form corner-sharing CrO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Rb(2), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Rb(2), one Rb(3), one Rb(4), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Cr(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), and one Cr(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(3), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Rb(4), one Cr(3), and one Cr(4) atom. In the ninth O site, O(9) is bonded in a single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Cr(3) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), one Rb(4), and one Cr(3) atom. In the eleventh O site, O(11) is bonded in a distorted single-bond geometry to one Rb(3), one Rb(4), and one Cr(3) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(3), one Rb(4), and one Cr(4) atom. In the thirteenth O site, O(13) is bonded in a single-bond geometry to one Rb(2), one Rb(4), and one Cr(4) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Rb(4), two equivalent Rb(3), and one Cr(4) atom. is represented by the CIF file [CIF]
data_Rb2Cr2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.878
_cell_length_b   7.915
_cell_length_c   13.846
_cell_angle_alpha   82.613
_cell_angle_beta   89.084
_cell_angle_gamma   86.591
_symmetry_Int_Tables_number   1
_cell_volume   854.690
_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
  Rb  Rb0  1  0.889  0.879  0.865  1.0
  Rb  Rb1  1  0.111  0.121  0.135  1.0
  Rb  Rb2  1  0.781  0.621  0.157  1.0
  Rb  Rb3  1  0.219  0.379  0.843  1.0
  Rb  Rb4  1  0.441  0.806  0.658  1.0
  Rb  Rb5  1  0.559  0.194  0.342  1.0
  Rb  Rb6  1  0.216  0.708  0.369  1.0
  Rb  Rb7  1  0.784  0.292  0.631  1.0
  Cr  Cr8  1  0.715  0.391  0.890  1.0
  Cr  Cr9  1  0.285  0.609  0.110  1.0
  Cr  Cr10  1  0.650  0.137  0.085  1.0
  Cr  Cr11  1  0.350  0.863  0.915  1.0
  Cr  Cr12  1  0.936  0.752  0.611  1.0
  Cr  Cr13  1  0.064  0.248  0.389  1.0
  Cr  Cr14  1  0.698  0.714  0.417  1.0
  Cr  Cr15  1  0.302  0.286  0.583  1.0
  O  O16  1  0.581  0.272  0.977  1.0
  O  O17  1  0.419  0.728  0.023  1.0
  O  O18  1  0.594  0.487  0.803  1.0
  O  O19  1  0.406  0.513  0.197  1.0
  O  O20  1  0.855  0.259  0.846  1.0
  O  O21  1  0.145  0.741  0.154  1.0
  O  O22  1  0.814  0.528  0.944  1.0
  O  O23  1  0.186  0.472  0.056  1.0
  O  O24  1  0.486  0.061  0.146  1.0
  O  O25  1  0.514  0.939  0.854  1.0
  O  O26  1  0.753  0.250  0.154  1.0
  O  O27  1  0.247  0.750  0.846  1.0
  O  O28  1  0.780  0.982  0.056  1.0
  O  O29  1  0.220  0.018  0.944  1.0
  O  O30  1  0.813  0.652  0.529  1.0
  O  O31  1  0.187  0.348  0.471  1.0
  O  O32  1  0.985  0.605  0.702  1.0
  O  O33  1  0.015  0.395  0.298  1.0
  O  O34  1  0.822  0.908  0.653  1.0
  O  O35  1  0.178  0.092  0.347  1.0
  O  O36  1  0.108  0.822  0.557  1.0
  O  O37  1  0.892  0.178  0.443  1.0
  O  O38  1  0.629  0.542  0.381  1.0
  O  O39  1  0.371  0.458  0.619  1.0
  O  O40  1  0.820  0.809  0.333  1.0
  O  O41  1  0.180  0.191  0.667  1.0
  O  O42  1  0.534  0.842  0.438  1.0
  O  O43  1  0.466  0.158  0.562  1.0
[/CIF]
.
The material described by Rb2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 8-coordinate geometry to one O(10), one O(3), one O(4), one O(5), one O(6), one O(9), and two equivalent O(7) atoms. In the second Rb site, Rb(2) is bonded in a 9-coordinate geometry to one O(1), one O(12), one O(13), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(9) atom. In the third Rb site, Rb(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(2), one O(5), one O(6), and two equivalent O(14) atoms. In the fourth Rb site, Rb(4) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(2), one O(3), one O(8), and one O(9) atom. There are four inequivalent Cr sites. In the first Cr site, 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. In the second Cr site, Cr(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form corner-sharing CrO4 tetrahedra. In the third Cr site, Cr(3) is bonded to one O(10), one O(11), one O(8), and one O(9) atom to form corner-sharing CrO4 tetrahedra. In the fourth Cr site, Cr(4) is bonded to one O(12), one O(13), one O(14), and one O(8) atom to form corner-sharing CrO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Rb(2), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Rb(2), one Rb(3), one Rb(4), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), and one Cr(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), and one Cr(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(2), one Rb(3), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Rb(2), two equivalent Rb(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Rb(4), one Cr(3), and one Cr(4) atom. In the ninth O site, O(9) is bonded in a single-bond geometry to one Rb(1), one Rb(2), one Rb(4), and one Cr(3) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), one Rb(4), and one Cr(3) atom. In the eleventh O site, O(11) is bonded in a distorted single-bond geometry to one Rb(3), one Rb(4), and one Cr(3) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(3), one Rb(4), and one Cr(4) atom. In the thirteenth O site, O(13) is bonded in a single-bond geometry to one Rb(2), one Rb(4), and one Cr(4) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Rb(4), two equivalent Rb(3), and one Cr(4) atom. is represented by the CIF file [CIF]
data_Rb2Cr2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.878
_cell_length_b   7.915
_cell_length_c   13.846
_cell_angle_alpha   82.613
_cell_angle_beta   89.084
_cell_angle_gamma   86.591
_symmetry_Int_Tables_number   1
_cell_volume   854.690
_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
  Rb  Rb0  1  0.889  0.879  0.865  1.0
  Rb  Rb1  1  0.111  0.121  0.135  1.0
  Rb  Rb2  1  0.781  0.621  0.157  1.0
  Rb  Rb3  1  0.219  0.379  0.843  1.0
  Rb  Rb4  1  0.441  0.806  0.658  1.0
  Rb  Rb5  1  0.559  0.194  0.342  1.0
  Rb  Rb6  1  0.216  0.708  0.369  1.0
  Rb  Rb7  1  0.784  0.292  0.631  1.0
  Cr  Cr8  1  0.715  0.391  0.890  1.0
  Cr  Cr9  1  0.285  0.609  0.110  1.0
  Cr  Cr10  1  0.650  0.137  0.085  1.0
  Cr  Cr11  1  0.350  0.863  0.915  1.0
  Cr  Cr12  1  0.936  0.752  0.611  1.0
  Cr  Cr13  1  0.064  0.248  0.389  1.0
  Cr  Cr14  1  0.698  0.714  0.417  1.0
  Cr  Cr15  1  0.302  0.286  0.583  1.0
  O  O16  1  0.581  0.272  0.977  1.0
  O  O17  1  0.419  0.728  0.023  1.0
  O  O18  1  0.594  0.487  0.803  1.0
  O  O19  1  0.406  0.513  0.197  1.0
  O  O20  1  0.855  0.259  0.846  1.0
  O  O21  1  0.145  0.741  0.154  1.0
  O  O22  1  0.814  0.528  0.944  1.0
  O  O23  1  0.186  0.472  0.056  1.0
  O  O24  1  0.486  0.061  0.146  1.0
  O  O25  1  0.514  0.939  0.854  1.0
  O  O26  1  0.753  0.250  0.154  1.0
  O  O27  1  0.247  0.750  0.846  1.0
  O  O28  1  0.780  0.982  0.056  1.0
  O  O29  1  0.220  0.018  0.944  1.0
  O  O30  1  0.813  0.652  0.529  1.0
  O  O31  1  0.187  0.348  0.471  1.0
  O  O32  1  0.985  0.605  0.702  1.0
  O  O33  1  0.015  0.395  0.298  1.0
  O  O34  1  0.822  0.908  0.653  1.0
  O  O35  1  0.178  0.092  0.347  1.0
  O  O36  1  0.108  0.822  0.557  1.0
  O  O37  1  0.892  0.178  0.443  1.0
  O  O38  1  0.629  0.542  0.381  1.0
  O  O39  1  0.371  0.458  0.619  1.0
  O  O40  1  0.820  0.809  0.333  1.0
  O  O41  1  0.180  0.191  0.667  1.0
  O  O42  1  0.534  0.842  0.438  1.0
  O  O43  1  0.466  0.158  0.562  1.0
[/CIF]
.