The material described by Na2CoP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(5), two equivalent O(1), and two equivalent O(6) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. Co(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form CoO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Co(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with three equivalent Co(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Co(1), and one P(1) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one P(1) atom. In the third O site, O(6) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Co(1), and one P(2) atom. In the fourth O site, O(7) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(1) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Co(1), and one P(2) atom. In the sixth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Co(1), and one P(2) atom. In the seventh O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Co(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2CoP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.700
_cell_length_b   5.261
_cell_length_c   10.222
_cell_angle_alpha   60.544
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   641.554
_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
  Na  Na0  1  0.296  0.591  0.144  1.0
  Na  Na1  1  0.204  0.591  0.644  1.0
  Na  Na2  1  0.704  0.409  0.856  1.0
  Na  Na3  1  0.796  0.409  0.356  1.0
  Na  Na4  1  0.607  0.071  0.636  1.0
  Na  Na5  1  0.893  0.071  0.136  1.0
  Na  Na6  1  0.393  0.929  0.364  1.0
  Na  Na7  1  0.107  0.929  0.864  1.0
  Co  Co8  1  0.332  0.963  0.738  1.0
  Co  Co9  1  0.168  0.963  0.238  1.0
  Co  Co10  1  0.668  0.037  0.262  1.0
  Co  Co11  1  0.832  0.037  0.762  1.0
  P  P12  1  0.041  0.468  0.233  1.0
  P  P13  1  0.459  0.468  0.733  1.0
  P  P14  1  0.959  0.532  0.767  1.0
  P  P15  1  0.541  0.532  0.267  1.0
  P  P16  1  0.190  0.284  0.452  1.0
  P  P17  1  0.310  0.284  0.952  1.0
  P  P18  1  0.810  0.716  0.548  1.0
  P  P19  1  0.690  0.716  0.048  1.0
  O  O20  1  0.228  0.590  0.412  1.0
  O  O21  1  0.272  0.590  0.912  1.0
  O  O22  1  0.772  0.410  0.588  1.0
  O  O23  1  0.728  0.410  0.088  1.0
  O  O24  1  0.236  0.159  0.359  1.0
  O  O25  1  0.264  0.159  0.859  1.0
  O  O26  1  0.764  0.841  0.641  1.0
  O  O27  1  0.736  0.841  0.141  1.0
  O  O28  1  0.052  0.222  0.193  1.0
  O  O29  1  0.448  0.222  0.693  1.0
  O  O30  1  0.948  0.778  0.807  1.0
  O  O31  1  0.552  0.778  0.307  1.0
  O  O32  1  0.115  0.718  0.144  1.0
  O  O33  1  0.385  0.718  0.644  1.0
  O  O34  1  0.885  0.282  0.856  1.0
  O  O35  1  0.615  0.282  0.356  1.0
  O  O36  1  0.937  0.568  0.225  1.0
  O  O37  1  0.563  0.568  0.725  1.0
  O  O38  1  0.063  0.432  0.775  1.0
  O  O39  1  0.437  0.432  0.275  1.0
  O  O40  1  0.198  0.076  0.623  1.0
  O  O41  1  0.302  0.076  0.123  1.0
  O  O42  1  0.802  0.924  0.377  1.0
  O  O43  1  0.698  0.924  0.877  1.0
  O  O44  1  0.074  0.322  0.412  1.0
  O  O45  1  0.426  0.322  0.912  1.0
  O  O46  1  0.926  0.678  0.588  1.0
  O  O47  1  0.574  0.678  0.088  1.0
[/CIF]
.
The material described by Na2CoP2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(5), two equivalent O(1), and two equivalent O(6) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. Co(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form CoO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Co(1)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with three equivalent Co(1)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Co(1), and one P(1) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one P(1) atom. In the third O site, O(6) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Co(1), and one P(2) atom. In the fourth O site, O(7) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(1) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Co(1), and one P(2) atom. In the sixth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Co(1), and one P(2) atom. In the seventh O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Co(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2CoP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.700
_cell_length_b   5.261
_cell_length_c   10.222
_cell_angle_alpha   60.544
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   641.554
_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
  Na  Na0  1  0.296  0.591  0.144  1.0
  Na  Na1  1  0.204  0.591  0.644  1.0
  Na  Na2  1  0.704  0.409  0.856  1.0
  Na  Na3  1  0.796  0.409  0.356  1.0
  Na  Na4  1  0.607  0.071  0.636  1.0
  Na  Na5  1  0.893  0.071  0.136  1.0
  Na  Na6  1  0.393  0.929  0.364  1.0
  Na  Na7  1  0.107  0.929  0.864  1.0
  Co  Co8  1  0.332  0.963  0.738  1.0
  Co  Co9  1  0.168  0.963  0.238  1.0
  Co  Co10  1  0.668  0.037  0.262  1.0
  Co  Co11  1  0.832  0.037  0.762  1.0
  P  P12  1  0.041  0.468  0.233  1.0
  P  P13  1  0.459  0.468  0.733  1.0
  P  P14  1  0.959  0.532  0.767  1.0
  P  P15  1  0.541  0.532  0.267  1.0
  P  P16  1  0.190  0.284  0.452  1.0
  P  P17  1  0.310  0.284  0.952  1.0
  P  P18  1  0.810  0.716  0.548  1.0
  P  P19  1  0.690  0.716  0.048  1.0
  O  O20  1  0.228  0.590  0.412  1.0
  O  O21  1  0.272  0.590  0.912  1.0
  O  O22  1  0.772  0.410  0.588  1.0
  O  O23  1  0.728  0.410  0.088  1.0
  O  O24  1  0.236  0.159  0.359  1.0
  O  O25  1  0.264  0.159  0.859  1.0
  O  O26  1  0.764  0.841  0.641  1.0
  O  O27  1  0.736  0.841  0.141  1.0
  O  O28  1  0.052  0.222  0.193  1.0
  O  O29  1  0.448  0.222  0.693  1.0
  O  O30  1  0.948  0.778  0.807  1.0
  O  O31  1  0.552  0.778  0.307  1.0
  O  O32  1  0.115  0.718  0.144  1.0
  O  O33  1  0.385  0.718  0.644  1.0
  O  O34  1  0.885  0.282  0.856  1.0
  O  O35  1  0.615  0.282  0.356  1.0
  O  O36  1  0.937  0.568  0.225  1.0
  O  O37  1  0.563  0.568  0.725  1.0
  O  O38  1  0.063  0.432  0.775  1.0
  O  O39  1  0.437  0.432  0.275  1.0
  O  O40  1  0.198  0.076  0.623  1.0
  O  O41  1  0.302  0.076  0.123  1.0
  O  O42  1  0.802  0.924  0.377  1.0
  O  O43  1  0.698  0.924  0.877  1.0
  O  O44  1  0.074  0.322  0.412  1.0
  O  O45  1  0.426  0.322  0.912  1.0
  O  O46  1  0.926  0.678  0.588  1.0
  O  O47  1  0.574  0.678  0.088  1.0
[/CIF]
.