The compound described by Na2CoSiCO7 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(10), one O(14), one O(17), one O(6), and two equivalent O(21) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(1)O7 pentagonal bipyramids,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(3)O7 pentagonal bipyramid,  an edgeedge with one Si(1)O4 tetrahedra, and  a faceface with one Na(4)O7 pentagonal bipyramid. In the second Na site, Na(2) is bonded to one O(13), one O(18), one O(2), one O(5), one O(9), and two equivalent O(22) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(2)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(4)O7 pentagonal bipyramid,  an edgeedge with one Co(3)O4 tetrahedra,  an edgeedge with one Si(2)O4 tetrahedra, and  a faceface with one Na(3)O7 pentagonal bipyramid. In the third Na site, Na(3) is bonded to one O(1), one O(13), one O(17), one O(5), one O(9), and two equivalent O(23) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(3)O7 pentagonal bipyramids,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid,  an edgeedge with one Co(3)O4 tetrahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  a faceface with one Na(2)O7 pentagonal bipyramid. In the fourth Na site, Na(4) is bonded to one O(10), one O(14), one O(18), one O(2), one O(6), and two equivalent O(24) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(4)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one Si(2)O4 tetrahedra, and  a faceface with one Na(1)O7 pentagonal bipyramid. In the fifth Na site, Na(5) is bonded to one O(11), one O(15), one O(19), one O(3), one O(7), and two equivalent O(25) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(5)O7 pentagonal bipyramids,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(7)O7 pentagonal bipyramid,  an edgeedge with one Co(4)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, and  a faceface with one Na(8)O7 pentagonal bipyramid. In the sixth Na site, Na(6) is bonded to one O(12), one O(16), one O(20), one O(4), one O(8), and two equivalent O(26) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(6)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(8)O7 pentagonal bipyramid,  an edgeedge with one Co(2)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra, and  a faceface with one Na(7)O7 pentagonal bipyramid. In the seventh Na site, Na(7) is bonded to one O(12), one O(16), one O(19), one O(3), one O(8), and two equivalent O(27) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(7)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(5)O7 pentagonal bipyramid,  an edgeedge with one Co(2)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, and  a faceface with one Na(6)O7 pentagonal bipyramid. In the eighth Na site, Na(8) is bonded to one O(11), one O(15), one O(20), one O(4), one O(7), and two equivalent O(28) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(8)O7 pentagonal bipyramids,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(6)O7 pentagonal bipyramid,  an edgeedge with one Co(4)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra, and  a faceface with one Na(5)O7 pentagonal bipyramid. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded in a 5-coordinate geometry to one O(14), one O(20), one O(21), one O(24), and one O(6) atom. In the second Co site, Co(2) is bonded to one O(16), one O(18), one O(26), and one O(27) atom to form distorted CoO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(4)O7 pentagonal bipyramid,  a cornercorner with one Na(6)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Na(6)O7 pentagonal bipyramid, and  an edgeedge with one Na(7)O7 pentagonal bipyramid. In the third Co site, Co(3) is bonded to one O(13), one O(19), one O(22), and one O(23) atom to form distorted CoO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid, and  an edgeedge with one Na(3)O7 pentagonal bipyramid. In the fourth Co site, Co(4) is bonded to one O(15), one O(17), one O(25), and one O(28) atom to form distorted CoO4 tetrahedra that share  a cornercorner with one Na(1)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(8)O7 pentagonal bipyramid,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Na(5)O7 pentagonal bipyramid, and  an edgeedge with one Na(8)O7 pentagonal bipyramid. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(15), one O(17), one O(21), and one O(23) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(8)O7 pentagonal bipyramid,  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(4)O4 tetrahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid, and  an edgeedge with one Na(3)O7 pentagonal bipyramid. In the second Si site, Si(2) is bonded to one O(16), one O(18), one O(22), and one O(24) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(4)O7 pentagonal bipyramid,  a cornercorner with one Na(6)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(2)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid, and  an edgeedge with one Na(4)O7 pentagonal bipyramid. In the third Si site, Si(3) is bonded to one O(13), one O(19), one O(25), and one O(27) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra, corners with two equivalent Co(3)O4 tetrahedra,  an edgeedge with one Na(5)O7 pentagonal bipyramid, and  an edgeedge with one Na(7)O7 pentagonal bipyramid. In the fourth Si site, Si(4) is bonded to one O(14), one O(20), one O(26), and one O(28) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O7 pentagonal bipyramid,  a cornercorner with one Na(4)O7 pentagonal bipyramid,  a cornercorner with one Na(6)O7 pentagonal bipyramid,  a cornercorner with one Na(8)O7 pentagonal bipyramid,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra,  an edgeedge with one Na(6)O7 pentagonal bipyramid, and  an edgeedge with one Na(8)O7 pentagonal bipyramid. There are four inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(4), one O(5), and one O(9) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(10), one O(3), and one O(6) atom. In the third C site, C(3) is bonded in a trigonal planar geometry to one O(11), one O(2), and one O(7) atom. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one O(1), one O(12), and one O(8) atom. There are twenty-eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Na(3), and one C(4) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(2), one Na(4), and one C(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(5), one Na(7), and one C(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(6), one Na(8), and one C(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Na(3), and one C(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Na(4), one Co(1), and one C(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(5), one Na(8), and one C(3) atom. In the eighth O site, O(8) is bonded in a 1-coordinate geometry to one Na(6), one Na(7), and one C(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(2), one Na(3), and one C(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(1), one Na(4), and one C(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(5), one Na(8), and one C(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Na(6), one Na(7), and one C(4) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(3), one Co(3), and one Si(3) atom. In the fourteenth O site, O(14) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(4), one Co(1), and one Si(4) atom. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one Na(5), one Na(8), one Co(4), and one Si(1) atom. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Na(6), one Na(7), one Co(2), and one Si(2) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one Co(4), and one Si(1) atom. In the eighteenth O site, O(18) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one Co(2), and one Si(2) atom. In the nineteenth O site, O(19) is bonded in a 4-coordinate geometry to one Na(5), one Na(7), one Co(3), and one Si(3) atom. In the twentieth O site, O(20) is bonded in a 4-coordinate geometry to one Na(6), one Na(8), one Co(1), and one Si(4) atom. In the twenty-first O site, O(21) is bonded in a 2-coordinate geometry to two equivalent Na(1), one Co(1), and one Si(1) atom. In the twenty-second O site, O(22) is bonded in a 2-coordinate geometry to two equivalent Na(2), one Co(3), and one Si(2) atom. In the twenty-third O site, O(23) is bonded in a 2-coordinate geometry to two equivalent Na(3), one Co(3), and one Si(1) atom. In the twenty-fourth O site, O(24) is bonded in a 2-coordinate geometry to two equivalent Na(4), one Co(1), and one Si(2) atom. In the twenty-fifth O site, O(25) is bonded in a 2-coordinate geometry to two equivalent Na(5), one Co(4), and one Si(3) atom. In the twenty-sixth O site, O(26) is bonded in a 2-coordinate geometry to two equivalent Na(6), one Co(2), and one Si(4) atom. In the twenty-seventh O site, O(27) is bonded in a 2-coordinate geometry to two equivalent Na(7), one Co(2), and one Si(3) atom. In the twenty-eighth O site, O(28) is bonded in a 2-coordinate geometry to two equivalent Na(8), one Co(4), and one Si(4) atom. is represented by the CIF file [CIF]
data_Na2CoSiCO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.133
_cell_length_b   6.267
_cell_length_c   9.781
_cell_angle_alpha   89.962
_cell_angle_beta   88.693
_cell_angle_gamma   89.964
_symmetry_Int_Tables_number   1
_cell_volume   314.611
_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
  C  C0  1  0.264  0.750  0.063  1.0
  C  C1  1  0.737  0.250  0.940  1.0
  Co  Co2  1  0.188  0.750  0.394  1.0
  Co  Co3  1  0.813  0.250  0.603  1.0
  Na  Na4  1  0.752  1.000  0.243  1.0
  Na  Na5  1  0.755  0.500  0.243  1.0
  Na  Na6  1  0.245  0.500  0.758  1.0
  Na  Na7  1  0.248  0.000  0.758  1.0
  O  O8  1  0.747  0.250  0.070  1.0
  O  O9  1  0.242  0.750  0.933  1.0
  O  O10  1  0.059  0.751  0.140  1.0
  O  O11  1  0.947  0.249  0.867  1.0
  O  O12  1  0.489  0.749  0.116  1.0
  O  O13  1  0.516  0.250  0.882  1.0
  O  O14  1  0.815  0.751  0.420  1.0
  O  O15  1  0.185  0.249  0.579  1.0
  O  O16  1  0.644  0.250  0.431  1.0
  O  O17  1  0.356  0.750  0.566  1.0
  O  O18  1  0.245  0.033  0.339  1.0
  O  O19  1  0.242  0.467  0.339  1.0
  O  O20  1  0.758  0.533  0.659  1.0
  O  O21  1  0.755  0.968  0.659  1.0
  Si  Si22  1  0.321  0.250  0.425  1.0
  Si  Si23  1  0.678  0.750  0.574  1.0
[/CIF]
.
The compound described by Na2CoSiCO7 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(10), one O(14), one O(17), one O(6), and two equivalent O(21) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(1)O7 pentagonal bipyramids,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(3)O7 pentagonal bipyramid,  an edgeedge with one Si(1)O4 tetrahedra, and  a faceface with one Na(4)O7 pentagonal bipyramid. In the second Na site, Na(2) is bonded to one O(13), one O(18), one O(2), one O(5), one O(9), and two equivalent O(22) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(2)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(4)O7 pentagonal bipyramid,  an edgeedge with one Co(3)O4 tetrahedra,  an edgeedge with one Si(2)O4 tetrahedra, and  a faceface with one Na(3)O7 pentagonal bipyramid. In the third Na site, Na(3) is bonded to one O(1), one O(13), one O(17), one O(5), one O(9), and two equivalent O(23) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(3)O7 pentagonal bipyramids,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid,  an edgeedge with one Co(3)O4 tetrahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  a faceface with one Na(2)O7 pentagonal bipyramid. In the fourth Na site, Na(4) is bonded to one O(10), one O(14), one O(18), one O(2), one O(6), and two equivalent O(24) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(4)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one Si(2)O4 tetrahedra, and  a faceface with one Na(1)O7 pentagonal bipyramid. In the fifth Na site, Na(5) is bonded to one O(11), one O(15), one O(19), one O(3), one O(7), and two equivalent O(25) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(5)O7 pentagonal bipyramids,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(7)O7 pentagonal bipyramid,  an edgeedge with one Co(4)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, and  a faceface with one Na(8)O7 pentagonal bipyramid. In the sixth Na site, Na(6) is bonded to one O(12), one O(16), one O(20), one O(4), one O(8), and two equivalent O(26) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(6)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(8)O7 pentagonal bipyramid,  an edgeedge with one Co(2)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra, and  a faceface with one Na(7)O7 pentagonal bipyramid. In the seventh Na site, Na(7) is bonded to one O(12), one O(16), one O(19), one O(3), one O(8), and two equivalent O(27) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(7)O7 pentagonal bipyramids,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(3)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  an edgeedge with one Na(5)O7 pentagonal bipyramid,  an edgeedge with one Co(2)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, and  a faceface with one Na(6)O7 pentagonal bipyramid. In the eighth Na site, Na(8) is bonded to one O(11), one O(15), one O(20), one O(4), one O(7), and two equivalent O(28) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(8)O7 pentagonal bipyramids,  a cornercorner with one Co(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  an edgeedge with one Na(6)O7 pentagonal bipyramid,  an edgeedge with one Co(4)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra, and  a faceface with one Na(5)O7 pentagonal bipyramid. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded in a 5-coordinate geometry to one O(14), one O(20), one O(21), one O(24), and one O(6) atom. In the second Co site, Co(2) is bonded to one O(16), one O(18), one O(26), and one O(27) atom to form distorted CoO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(4)O7 pentagonal bipyramid,  a cornercorner with one Na(6)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Na(6)O7 pentagonal bipyramid, and  an edgeedge with one Na(7)O7 pentagonal bipyramid. In the third Co site, Co(3) is bonded to one O(13), one O(19), one O(22), and one O(23) atom to form distorted CoO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid, and  an edgeedge with one Na(3)O7 pentagonal bipyramid. In the fourth Co site, Co(4) is bonded to one O(15), one O(17), one O(25), and one O(28) atom to form distorted CoO4 tetrahedra that share  a cornercorner with one Na(1)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(8)O7 pentagonal bipyramid,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Na(5)O7 pentagonal bipyramid, and  an edgeedge with one Na(8)O7 pentagonal bipyramid. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(15), one O(17), one O(21), and one O(23) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(8)O7 pentagonal bipyramid,  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(4)O4 tetrahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid, and  an edgeedge with one Na(3)O7 pentagonal bipyramid. In the second Si site, Si(2) is bonded to one O(16), one O(18), one O(22), and one O(24) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(4)O7 pentagonal bipyramid,  a cornercorner with one Na(6)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Co(3)O4 tetrahedra, corners with two equivalent Co(2)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid, and  an edgeedge with one Na(4)O7 pentagonal bipyramid. In the third Si site, Si(3) is bonded to one O(13), one O(19), one O(25), and one O(27) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid,  a cornercorner with one Na(3)O7 pentagonal bipyramid,  a cornercorner with one Na(5)O7 pentagonal bipyramid,  a cornercorner with one Na(7)O7 pentagonal bipyramid,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra, corners with two equivalent Co(3)O4 tetrahedra,  an edgeedge with one Na(5)O7 pentagonal bipyramid, and  an edgeedge with one Na(7)O7 pentagonal bipyramid. In the fourth Si site, Si(4) is bonded to one O(14), one O(20), one O(26), and one O(28) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O7 pentagonal bipyramid,  a cornercorner with one Na(4)O7 pentagonal bipyramid,  a cornercorner with one Na(6)O7 pentagonal bipyramid,  a cornercorner with one Na(8)O7 pentagonal bipyramid,  a cornercorner with one Co(2)O4 tetrahedra,  a cornercorner with one Co(4)O4 tetrahedra,  an edgeedge with one Na(6)O7 pentagonal bipyramid, and  an edgeedge with one Na(8)O7 pentagonal bipyramid. There are four inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one O(4), one O(5), and one O(9) atom. In the second C site, C(2) is bonded in a trigonal planar geometry to one O(10), one O(3), and one O(6) atom. In the third C site, C(3) is bonded in a trigonal planar geometry to one O(11), one O(2), and one O(7) atom. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one O(1), one O(12), and one O(8) atom. There are twenty-eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Na(3), and one C(4) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(2), one Na(4), and one C(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(5), one Na(7), and one C(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(6), one Na(8), and one C(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Na(3), and one C(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Na(4), one Co(1), and one C(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(5), one Na(8), and one C(3) atom. In the eighth O site, O(8) is bonded in a 1-coordinate geometry to one Na(6), one Na(7), and one C(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(2), one Na(3), and one C(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(1), one Na(4), and one C(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(5), one Na(8), and one C(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Na(6), one Na(7), and one C(4) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(3), one Co(3), and one Si(3) atom. In the fourteenth O site, O(14) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(4), one Co(1), and one Si(4) atom. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one Na(5), one Na(8), one Co(4), and one Si(1) atom. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Na(6), one Na(7), one Co(2), and one Si(2) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one Co(4), and one Si(1) atom. In the eighteenth O site, O(18) is bonded in a 4-coordinate geometry to one Na(2), one Na(4), one Co(2), and one Si(2) atom. In the nineteenth O site, O(19) is bonded in a 4-coordinate geometry to one Na(5), one Na(7), one Co(3), and one Si(3) atom. In the twentieth O site, O(20) is bonded in a 4-coordinate geometry to one Na(6), one Na(8), one Co(1), and one Si(4) atom. In the twenty-first O site, O(21) is bonded in a 2-coordinate geometry to two equivalent Na(1), one Co(1), and one Si(1) atom. In the twenty-second O site, O(22) is bonded in a 2-coordinate geometry to two equivalent Na(2), one Co(3), and one Si(2) atom. In the twenty-third O site, O(23) is bonded in a 2-coordinate geometry to two equivalent Na(3), one Co(3), and one Si(1) atom. In the twenty-fourth O site, O(24) is bonded in a 2-coordinate geometry to two equivalent Na(4), one Co(1), and one Si(2) atom. In the twenty-fifth O site, O(25) is bonded in a 2-coordinate geometry to two equivalent Na(5), one Co(4), and one Si(3) atom. In the twenty-sixth O site, O(26) is bonded in a 2-coordinate geometry to two equivalent Na(6), one Co(2), and one Si(4) atom. In the twenty-seventh O site, O(27) is bonded in a 2-coordinate geometry to two equivalent Na(7), one Co(2), and one Si(3) atom. In the twenty-eighth O site, O(28) is bonded in a 2-coordinate geometry to two equivalent Na(8), one Co(4), and one Si(4) atom. is represented by the CIF file [CIF]
data_Na2CoSiCO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.133
_cell_length_b   6.267
_cell_length_c   9.781
_cell_angle_alpha   89.962
_cell_angle_beta   88.693
_cell_angle_gamma   89.964
_symmetry_Int_Tables_number   1
_cell_volume   314.611
_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
  C  C0  1  0.264  0.750  0.063  1.0
  C  C1  1  0.737  0.250  0.940  1.0
  Co  Co2  1  0.188  0.750  0.394  1.0
  Co  Co3  1  0.813  0.250  0.603  1.0
  Na  Na4  1  0.752  1.000  0.243  1.0
  Na  Na5  1  0.755  0.500  0.243  1.0
  Na  Na6  1  0.245  0.500  0.758  1.0
  Na  Na7  1  0.248  0.000  0.758  1.0
  O  O8  1  0.747  0.250  0.070  1.0
  O  O9  1  0.242  0.750  0.933  1.0
  O  O10  1  0.059  0.751  0.140  1.0
  O  O11  1  0.947  0.249  0.867  1.0
  O  O12  1  0.489  0.749  0.116  1.0
  O  O13  1  0.516  0.250  0.882  1.0
  O  O14  1  0.815  0.751  0.420  1.0
  O  O15  1  0.185  0.249  0.579  1.0
  O  O16  1  0.644  0.250  0.431  1.0
  O  O17  1  0.356  0.750  0.566  1.0
  O  O18  1  0.245  0.033  0.339  1.0
  O  O19  1  0.242  0.467  0.339  1.0
  O  O20  1  0.758  0.533  0.659  1.0
  O  O21  1  0.755  0.968  0.659  1.0
  Si  Si22  1  0.321  0.250  0.425  1.0
  Si  Si23  1  0.678  0.750  0.574  1.0
[/CIF]
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