The structure described by Na3CrCAsO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent Cr(1)O5 square pyramids, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one As(1)O4 tetrahedra,  a faceface with one Na(2)O7 pentagonal bipyramid, and  a faceface with one Cr(1)O5 square pyramid. Cr(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted CrO5 square pyramids that share corners with four equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent As(1)O4 tetrahedra, and faces with two equivalent Na(2)O7 pentagonal bipyramids. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. As(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form AsO4 tetrahedra that share corners with four equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent Cr(1)O5 square pyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cr(1), and one C(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one C(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cr(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted tetrahedral geometry to two equivalent Na(2), one Cr(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Cr(1), and one As(1) atom. is represented by the CIF file [CIF]
data_Na3CrAsCO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.324
_cell_length_b   6.867
_cell_length_c   5.353
_cell_angle_alpha   90.002
_cell_angle_beta   88.093
_cell_angle_gamma   90.004
_symmetry_Int_Tables_number   1
_cell_volume   342.546
_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
  Na  Na0  1  0.084  0.250  0.793  1.0
  Na  Na1  1  0.256  0.002  0.251  1.0
  Na  Na2  1  0.256  0.498  0.251  1.0
  Na  Na3  1  0.744  0.502  0.749  1.0
  Na  Na4  1  0.744  0.998  0.749  1.0
  Na  Na5  1  0.916  0.750  0.207  1.0
  Cr  Cr6  1  0.347  0.750  0.771  1.0
  Cr  Cr7  1  0.653  0.250  0.228  1.0
  As  As8  1  0.419  0.250  0.687  1.0
  As  As9  1  0.581  0.750  0.313  1.0
  C  C10  1  0.049  0.750  0.710  1.0
  C  C11  1  0.951  0.250  0.290  1.0
  O  O12  1  0.089  0.250  0.253  1.0
  O  O13  1  0.131  0.750  0.906  1.0
  O  O14  1  0.107  0.750  0.487  1.0
  O  O15  1  0.312  0.053  0.771  1.0
  O  O16  1  0.312  0.447  0.771  1.0
  O  O17  1  0.440  0.250  0.363  1.0
  O  O18  1  0.415  0.750  0.186  1.0
  O  O19  1  0.585  0.250  0.814  1.0
  O  O20  1  0.560  0.750  0.637  1.0
  O  O21  1  0.688  0.553  0.230  1.0
  O  O22  1  0.688  0.947  0.230  1.0
  O  O23  1  0.893  0.250  0.513  1.0
  O  O24  1  0.869  0.250  0.094  1.0
  O  O25  1  0.911  0.750  0.747  1.0
[/CIF]
.
The structure described by Na3CrCAsO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent Cr(1)O5 square pyramids, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one As(1)O4 tetrahedra,  a faceface with one Na(2)O7 pentagonal bipyramid, and  a faceface with one Cr(1)O5 square pyramid. Cr(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted CrO5 square pyramids that share corners with four equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent As(1)O4 tetrahedra, and faces with two equivalent Na(2)O7 pentagonal bipyramids. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. As(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form AsO4 tetrahedra that share corners with four equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent Cr(1)O5 square pyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cr(1), and one C(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one C(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cr(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted tetrahedral geometry to two equivalent Na(2), one Cr(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Cr(1), and one As(1) atom. is represented by the CIF file [CIF]
data_Na3CrAsCO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.324
_cell_length_b   6.867
_cell_length_c   5.353
_cell_angle_alpha   90.002
_cell_angle_beta   88.093
_cell_angle_gamma   90.004
_symmetry_Int_Tables_number   1
_cell_volume   342.546
_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
  Na  Na0  1  0.084  0.250  0.793  1.0
  Na  Na1  1  0.256  0.002  0.251  1.0
  Na  Na2  1  0.256  0.498  0.251  1.0
  Na  Na3  1  0.744  0.502  0.749  1.0
  Na  Na4  1  0.744  0.998  0.749  1.0
  Na  Na5  1  0.916  0.750  0.207  1.0
  Cr  Cr6  1  0.347  0.750  0.771  1.0
  Cr  Cr7  1  0.653  0.250  0.228  1.0
  As  As8  1  0.419  0.250  0.687  1.0
  As  As9  1  0.581  0.750  0.313  1.0
  C  C10  1  0.049  0.750  0.710  1.0
  C  C11  1  0.951  0.250  0.290  1.0
  O  O12  1  0.089  0.250  0.253  1.0
  O  O13  1  0.131  0.750  0.906  1.0
  O  O14  1  0.107  0.750  0.487  1.0
  O  O15  1  0.312  0.053  0.771  1.0
  O  O16  1  0.312  0.447  0.771  1.0
  O  O17  1  0.440  0.250  0.363  1.0
  O  O18  1  0.415  0.750  0.186  1.0
  O  O19  1  0.585  0.250  0.814  1.0
  O  O20  1  0.560  0.750  0.637  1.0
  O  O21  1  0.688  0.553  0.230  1.0
  O  O22  1  0.688  0.947  0.230  1.0
  O  O23  1  0.893  0.250  0.513  1.0
  O  O24  1  0.869  0.250  0.094  1.0
  O  O25  1  0.911  0.750  0.747  1.0
[/CIF]
.