The crystal structure described by K2CuP2O7 crystallizes in the orthorhombic P2_12_12 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and three equivalent O(4) atoms. Cu(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted CuO4 trigonal pyramids that share corners with four equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Cu(1)O4 trigonal pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent K(1), one Cu(1), and one P(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent K(1), one Cu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to three equivalent K(1) and one P(1) atom. is represented by the CIF card [CIF]
data_K2CuP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.424
_cell_length_b   8.060
_cell_length_c   8.053
_cell_angle_alpha   90.000
_cell_angle_beta   89.994
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   352.027
_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
  K  K0  1  0.492  0.334  0.166  1.0
  K  K1  1  0.508  0.166  0.666  1.0
  K  K2  1  0.492  0.666  0.834  1.0
  K  K3  1  0.508  0.834  0.334  1.0
  Cu  Cu4  1  0.002  0.500  0.500  1.0
  Cu  Cu5  1  0.998  1.000  0.000  1.0
  P  P6  1  0.982  0.366  0.866  1.0
  P  P7  1  0.018  0.134  0.366  1.0
  P  P8  1  0.982  0.634  0.134  1.0
  P  P9  1  0.018  0.866  0.634  1.0
  O  O10  1  0.879  0.500  0.000  1.0
  O  O11  1  0.121  0.000  0.500  1.0
  O  O12  1  0.860  0.577  0.295  1.0
  O  O13  1  0.140  0.923  0.795  1.0
  O  O14  1  0.860  0.423  0.705  1.0
  O  O15  1  0.140  0.077  0.205  1.0
  O  O16  1  0.141  0.705  0.577  1.0
  O  O17  1  0.859  0.795  0.078  1.0
  O  O18  1  0.141  0.295  0.422  1.0
  O  O19  1  0.859  0.205  0.923  1.0
  O  O20  1  0.256  0.366  0.866  1.0
  O  O21  1  0.744  0.134  0.366  1.0
  O  O22  1  0.256  0.634  0.134  1.0
  O  O23  1  0.744  0.866  0.634  1.0
[/CIF]
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The crystal structure described by K2CuP2O7 crystallizes in the orthorhombic P2_12_12 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and three equivalent O(4) atoms. Cu(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted CuO4 trigonal pyramids that share corners with four equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Cu(1)O4 trigonal pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent P(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent K(1), one Cu(1), and one P(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent K(1), one Cu(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to three equivalent K(1) and one P(1) atom. is represented by the CIF card [CIF]
data_K2CuP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.424
_cell_length_b   8.060
_cell_length_c   8.053
_cell_angle_alpha   90.000
_cell_angle_beta   89.994
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   352.027
_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
  K  K0  1  0.492  0.334  0.166  1.0
  K  K1  1  0.508  0.166  0.666  1.0
  K  K2  1  0.492  0.666  0.834  1.0
  K  K3  1  0.508  0.834  0.334  1.0
  Cu  Cu4  1  0.002  0.500  0.500  1.0
  Cu  Cu5  1  0.998  1.000  0.000  1.0
  P  P6  1  0.982  0.366  0.866  1.0
  P  P7  1  0.018  0.134  0.366  1.0
  P  P8  1  0.982  0.634  0.134  1.0
  P  P9  1  0.018  0.866  0.634  1.0
  O  O10  1  0.879  0.500  0.000  1.0
  O  O11  1  0.121  0.000  0.500  1.0
  O  O12  1  0.860  0.577  0.295  1.0
  O  O13  1  0.140  0.923  0.795  1.0
  O  O14  1  0.860  0.423  0.705  1.0
  O  O15  1  0.140  0.077  0.205  1.0
  O  O16  1  0.141  0.705  0.577  1.0
  O  O17  1  0.859  0.795  0.078  1.0
  O  O18  1  0.141  0.295  0.422  1.0
  O  O19  1  0.859  0.205  0.923  1.0
  O  O20  1  0.256  0.366  0.866  1.0
  O  O21  1  0.744  0.134  0.366  1.0
  O  O22  1  0.256  0.634  0.134  1.0
  O  O23  1  0.744  0.866  0.634  1.0
[/CIF]
.