The compound described by Cr5(Si2O7)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted square co-planar geometry to two equivalent O(5) and two equivalent O(7) atoms. In the second Cr site, Cr(2) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(4), and two equivalent O(2) atoms. In the third Cr site, Cr(3) is bonded to one O(4), one O(5), one O(7), and two equivalent O(6) atoms to form CrO5 trigonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Cr(3)O5 trigonal bipyramids. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Cr(3)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Cr(2) and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Cr(2) and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Cr(2), one Cr(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cr(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one Si(1) atom. is represented by the CIF card [CIF]
data_Cr5(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.436
_cell_length_b   7.920
_cell_length_c   5.772
_cell_angle_alpha   89.718
_cell_angle_beta   107.495
_cell_angle_gamma   112.620
_symmetry_Int_Tables_number   1
_cell_volume   296.878
_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
  Cr  Cr0  1  1.000  1.000  1.000  1.0
  Cr  Cr1  1  0.390  0.809  0.075  1.0
  Cr  Cr2  1  0.576  0.697  0.644  1.0
  Cr  Cr3  1  0.424  0.303  0.356  1.0
  Cr  Cr4  1  0.610  0.191  0.925  1.0
  Si  Si5  1  0.236  0.865  0.496  1.0
  Si  Si6  1  0.216  0.385  0.772  1.0
  Si  Si7  1  0.784  0.615  0.227  1.0
  Si  Si8  1  0.764  0.135  0.504  1.0
  O  O9  1  0.225  0.580  0.855  1.0
  O  O10  1  0.357  0.952  0.781  1.0
  O  O11  1  0.008  0.259  0.549  1.0
  O  O12  1  0.351  0.747  0.409  1.0
  O  O13  1  0.233  0.258  0.004  1.0
  O  O14  1  0.405  0.423  0.651  1.0
  O  O15  1  0.235  0.032  0.320  1.0
  O  O16  1  0.765  0.968  0.680  1.0
  O  O17  1  0.595  0.577  0.349  1.0
  O  O18  1  0.767  0.742  0.996  1.0
  O  O19  1  0.649  0.253  0.591  1.0
  O  O20  1  0.992  0.741  0.450  1.0
  O  O21  1  0.643  0.048  0.219  1.0
  O  O22  1  0.775  0.420  0.145  1.0
[/CIF]
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The compound described by Cr5(Si2O7)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted square co-planar geometry to two equivalent O(5) and two equivalent O(7) atoms. In the second Cr site, Cr(2) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(4), and two equivalent O(2) atoms. In the third Cr site, Cr(3) is bonded to one O(4), one O(5), one O(7), and two equivalent O(6) atoms to form CrO5 trigonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Cr(3)O5 trigonal bipyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Cr(3)O5 trigonal bipyramids. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Cr(3)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Cr(2) and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Cr(2) and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Cr(2), one Cr(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cr(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(3), and one Si(1) atom. is represented by the CIF card [CIF]
data_Cr5(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.436
_cell_length_b   7.920
_cell_length_c   5.772
_cell_angle_alpha   89.718
_cell_angle_beta   107.495
_cell_angle_gamma   112.620
_symmetry_Int_Tables_number   1
_cell_volume   296.878
_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
  Cr  Cr0  1  1.000  1.000  1.000  1.0
  Cr  Cr1  1  0.390  0.809  0.075  1.0
  Cr  Cr2  1  0.576  0.697  0.644  1.0
  Cr  Cr3  1  0.424  0.303  0.356  1.0
  Cr  Cr4  1  0.610  0.191  0.925  1.0
  Si  Si5  1  0.236  0.865  0.496  1.0
  Si  Si6  1  0.216  0.385  0.772  1.0
  Si  Si7  1  0.784  0.615  0.227  1.0
  Si  Si8  1  0.764  0.135  0.504  1.0
  O  O9  1  0.225  0.580  0.855  1.0
  O  O10  1  0.357  0.952  0.781  1.0
  O  O11  1  0.008  0.259  0.549  1.0
  O  O12  1  0.351  0.747  0.409  1.0
  O  O13  1  0.233  0.258  0.004  1.0
  O  O14  1  0.405  0.423  0.651  1.0
  O  O15  1  0.235  0.032  0.320  1.0
  O  O16  1  0.765  0.968  0.680  1.0
  O  O17  1  0.595  0.577  0.349  1.0
  O  O18  1  0.767  0.742  0.996  1.0
  O  O19  1  0.649  0.253  0.591  1.0
  O  O20  1  0.992  0.741  0.450  1.0
  O  O21  1  0.643  0.048  0.219  1.0
  O  O22  1  0.775  0.420  0.145  1.0
[/CIF]
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