The structure described by Na2Cu2Si4O11 crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. Cu(1) is bonded to one O(5), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO5 square pyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with two equivalent Cu(1)O5 square pyramids. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with three equivalent Cu(1)O5 square pyramids and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Cu(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Cu(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Na(1), one Cu(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a linear geometry to two equivalent Si(2) atoms. is represented by the CIF file [CIF]
data_Na2Cu2Si4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.246
_cell_length_b   6.364
_cell_length_c   8.361
_cell_angle_alpha   96.687
_cell_angle_beta   96.765
_cell_angle_gamma   100.803
_symmetry_Int_Tables_number   1
_cell_volume   269.554
_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
  Na  Na0  1  0.868  0.352  0.195  1.0
  Na  Na1  1  0.132  0.648  0.805  1.0
  Cu  Cu2  1  0.297  0.111  0.071  1.0
  Cu  Cu3  1  0.703  0.889  0.929  1.0
  Si  Si4  1  0.406  0.656  0.190  1.0
  Si  Si5  1  0.015  0.135  0.679  1.0
  Si  Si6  1  0.594  0.344  0.810  1.0
  Si  Si7  1  0.985  0.865  0.321  1.0
  O  O8  1  0.292  0.322  0.715  1.0
  O  O9  1  0.708  0.678  0.285  1.0
  O  O10  1  0.595  0.174  0.946  1.0
  O  O11  1  0.405  0.826  0.054  1.0
  O  O12  1  0.003  0.977  0.817  1.0
  O  O13  1  0.997  0.023  0.183  1.0
  O  O14  1  0.221  0.728  0.327  1.0
  O  O15  1  0.723  0.588  0.890  1.0
  O  O16  1  0.779  0.272  0.673  1.0
  O  O17  1  0.000  0.000  0.500  1.0
  O  O18  1  0.277  0.412  0.110  1.0
[/CIF]
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The structure described by Na2Cu2Si4O11 crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. Cu(1) is bonded to one O(5), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO5 square pyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with two equivalent Cu(1)O5 square pyramids. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with three equivalent Cu(1)O5 square pyramids and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Cu(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Cu(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Na(1), one Cu(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a linear geometry to two equivalent Si(2) atoms. is represented by the CIF file [CIF]
data_Na2Cu2Si4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.246
_cell_length_b   6.364
_cell_length_c   8.361
_cell_angle_alpha   96.687
_cell_angle_beta   96.765
_cell_angle_gamma   100.803
_symmetry_Int_Tables_number   1
_cell_volume   269.554
_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
  Na  Na0  1  0.868  0.352  0.195  1.0
  Na  Na1  1  0.132  0.648  0.805  1.0
  Cu  Cu2  1  0.297  0.111  0.071  1.0
  Cu  Cu3  1  0.703  0.889  0.929  1.0
  Si  Si4  1  0.406  0.656  0.190  1.0
  Si  Si5  1  0.015  0.135  0.679  1.0
  Si  Si6  1  0.594  0.344  0.810  1.0
  Si  Si7  1  0.985  0.865  0.321  1.0
  O  O8  1  0.292  0.322  0.715  1.0
  O  O9  1  0.708  0.678  0.285  1.0
  O  O10  1  0.595  0.174  0.946  1.0
  O  O11  1  0.405  0.826  0.054  1.0
  O  O12  1  0.003  0.977  0.817  1.0
  O  O13  1  0.997  0.023  0.183  1.0
  O  O14  1  0.221  0.728  0.327  1.0
  O  O15  1  0.723  0.588  0.890  1.0
  O  O16  1  0.779  0.272  0.673  1.0
  O  O17  1  0.000  0.000  0.500  1.0
  O  O18  1  0.277  0.412  0.110  1.0
[/CIF]
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