The structure described by Na7MgCu3O8 crystallizes in the triclinic P1 space group. There are seven inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(7), and one O(8) atom. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(7), and one O(8) atom. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(4), one O(6), and one O(8) atom. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(7) atom. In the fifth Na site, Na(5) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), one O(6), and one O(8) atom. In the sixth Na site, Na(6) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(6), and one O(7) atom. In the seventh Na site, Na(7) is bonded in a 4-coordinate geometry to one O(1), one O(6), one O(7), and one O(8) atom. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(4), one O(5), and one O(6) atom. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(3), one O(4), one O(5), and one O(6) atom. In the third Cu site, Cu(3) is bonded in a distorted rectangular see-saw-like geometry to one O(5), one O(6), one O(7), and one O(8) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one Na(1), one Na(3), one Na(4), one Na(5), one Na(6), one Na(7), and one Cu(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(4), one Na(6), one Mg(1), and one Cu(1) atom to form distorted ONa4MgCu pentagonal pyramids that share corners with three equivalent O(3)Na4Cu2 octahedra,  an edgeedge with one O(8)Na5Cu pentagonal pyramid, and  a faceface with one O(4)Na2MgCu2 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-72°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(5), one Cu(1), and one Cu(2) atom to form distorted ONa4Cu2 octahedra that share corners with two equivalent O(8)Na5Cu pentagonal pyramids, corners with three equivalent O(2)Na4MgCu pentagonal pyramids,  a cornercorner with one O(4)Na2MgCu2 trigonal bipyramid,  an edgeedge with one O(8)Na5Cu pentagonal pyramid, and  an edgeedge with one O(4)Na2MgCu2 trigonal bipyramid. In the fourth O site, O(4) is bonded to one Na(3), one Na(4), one Mg(1), one Cu(1), and one Cu(2) atom to form distorted ONa2MgCu2 trigonal bipyramids that share  a cornercorner with one O(3)Na4Cu2 octahedra,  a cornercorner with one O(8)Na5Cu pentagonal pyramid,  an edgeedge with one O(3)Na4Cu2 octahedra, and  a faceface with one O(2)Na4MgCu pentagonal pyramid. The corner-sharing octahedral tilt angles are 31°. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(4), one Na(5), one Mg(1), one Cu(2), and one Cu(3) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(3), one Na(5), one Na(6), one Na(7), one Mg(1), one Cu(2), and one Cu(3) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(6), one Na(7), and one Cu(3) atom. In the eighth O site, O(8) is bonded to one Na(1), one Na(2), one Na(3), one Na(5), one Na(7), and one Cu(3) atom to form distorted ONa5Cu pentagonal pyramids that share corners with two equivalent O(3)Na4Cu2 octahedra,  a cornercorner with one O(4)Na2MgCu2 trigonal bipyramid,  an edgeedge with one O(3)Na4Cu2 octahedra, and  an edgeedge with one O(2)Na4MgCu pentagonal pyramid. The corner-sharing octahedral tilt angles range from 21-39°. is represented by the CIF card [CIF]
data_Na7MgCu3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.787
_cell_length_b   6.719
_cell_length_c   7.744
_cell_angle_alpha   107.898
_cell_angle_beta   114.143
_cell_angle_gamma   87.816
_symmetry_Int_Tables_number   1
_cell_volume   260.158
_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  0.295  0.395  0.384  1.0
  Na  Na1  1  0.556  0.157  0.701  1.0
  Na  Na2  1  0.766  0.601  0.057  1.0
  Na  Na3  1  0.955  0.962  0.484  1.0
  Na  Na4  1  0.247  0.395  0.947  1.0
  Na  Na5  1  0.359  0.786  0.301  1.0
  Na  Na6  1  0.727  0.613  0.642  1.0
  Mg  Mg7  1  0.462  0.980  0.089  1.0
  Cu  Cu8  1  0.767  0.283  0.252  1.0
  Cu  Cu9  1  0.993  0.011  0.996  1.0
  Cu  Cu10  1  0.266  0.737  0.751  1.0
  O  O11  1  0.642  0.546  0.297  1.0
  O  O12  1  0.573  0.140  0.374  1.0
  O  O13  1  0.926  0.297  0.065  1.0
  O  O14  1  0.831  0.971  0.153  1.0
  O  O15  1  0.179  0.030  0.840  1.0
  O  O16  1  0.152  0.739  0.961  1.0
  O  O17  1  0.360  0.801  0.576  1.0
  O  O18  1  0.409  0.484  0.736  1.0
[/CIF]
.
The structure described by Na7MgCu3O8 crystallizes in the triclinic P1 space group. There are seven inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(7), and one O(8) atom. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(7), and one O(8) atom. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(4), one O(6), and one O(8) atom. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(7) atom. In the fifth Na site, Na(5) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), one O(6), and one O(8) atom. In the sixth Na site, Na(6) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(6), and one O(7) atom. In the seventh Na site, Na(7) is bonded in a 4-coordinate geometry to one O(1), one O(6), one O(7), and one O(8) atom. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(4), one O(5), and one O(6) atom. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to one O(3), one O(4), one O(5), and one O(6) atom. In the third Cu site, Cu(3) is bonded in a distorted rectangular see-saw-like geometry to one O(5), one O(6), one O(7), and one O(8) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one Na(1), one Na(3), one Na(4), one Na(5), one Na(6), one Na(7), and one Cu(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(4), one Na(6), one Mg(1), and one Cu(1) atom to form distorted ONa4MgCu pentagonal pyramids that share corners with three equivalent O(3)Na4Cu2 octahedra,  an edgeedge with one O(8)Na5Cu pentagonal pyramid, and  a faceface with one O(4)Na2MgCu2 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-72°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(5), one Cu(1), and one Cu(2) atom to form distorted ONa4Cu2 octahedra that share corners with two equivalent O(8)Na5Cu pentagonal pyramids, corners with three equivalent O(2)Na4MgCu pentagonal pyramids,  a cornercorner with one O(4)Na2MgCu2 trigonal bipyramid,  an edgeedge with one O(8)Na5Cu pentagonal pyramid, and  an edgeedge with one O(4)Na2MgCu2 trigonal bipyramid. In the fourth O site, O(4) is bonded to one Na(3), one Na(4), one Mg(1), one Cu(1), and one Cu(2) atom to form distorted ONa2MgCu2 trigonal bipyramids that share  a cornercorner with one O(3)Na4Cu2 octahedra,  a cornercorner with one O(8)Na5Cu pentagonal pyramid,  an edgeedge with one O(3)Na4Cu2 octahedra, and  a faceface with one O(2)Na4MgCu pentagonal pyramid. The corner-sharing octahedral tilt angles are 31°. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(4), one Na(5), one Mg(1), one Cu(2), and one Cu(3) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(3), one Na(5), one Na(6), one Na(7), one Mg(1), one Cu(2), and one Cu(3) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(6), one Na(7), and one Cu(3) atom. In the eighth O site, O(8) is bonded to one Na(1), one Na(2), one Na(3), one Na(5), one Na(7), and one Cu(3) atom to form distorted ONa5Cu pentagonal pyramids that share corners with two equivalent O(3)Na4Cu2 octahedra,  a cornercorner with one O(4)Na2MgCu2 trigonal bipyramid,  an edgeedge with one O(3)Na4Cu2 octahedra, and  an edgeedge with one O(2)Na4MgCu pentagonal pyramid. The corner-sharing octahedral tilt angles range from 21-39°. is represented by the CIF card [CIF]
data_Na7MgCu3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.787
_cell_length_b   6.719
_cell_length_c   7.744
_cell_angle_alpha   107.898
_cell_angle_beta   114.143
_cell_angle_gamma   87.816
_symmetry_Int_Tables_number   1
_cell_volume   260.158
_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  0.295  0.395  0.384  1.0
  Na  Na1  1  0.556  0.157  0.701  1.0
  Na  Na2  1  0.766  0.601  0.057  1.0
  Na  Na3  1  0.955  0.962  0.484  1.0
  Na  Na4  1  0.247  0.395  0.947  1.0
  Na  Na5  1  0.359  0.786  0.301  1.0
  Na  Na6  1  0.727  0.613  0.642  1.0
  Mg  Mg7  1  0.462  0.980  0.089  1.0
  Cu  Cu8  1  0.767  0.283  0.252  1.0
  Cu  Cu9  1  0.993  0.011  0.996  1.0
  Cu  Cu10  1  0.266  0.737  0.751  1.0
  O  O11  1  0.642  0.546  0.297  1.0
  O  O12  1  0.573  0.140  0.374  1.0
  O  O13  1  0.926  0.297  0.065  1.0
  O  O14  1  0.831  0.971  0.153  1.0
  O  O15  1  0.179  0.030  0.840  1.0
  O  O16  1  0.152  0.739  0.961  1.0
  O  O17  1  0.360  0.801  0.576  1.0
  O  O18  1  0.409  0.484  0.736  1.0
[/CIF]
.