The crystal structure described by KAlAs2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted KO8 hexagonal bipyramids that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, corners with four equivalent As(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 52°. In the second K site, K(2) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms. Al(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form AlO6 octahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid, corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid, corners with three equivalent Al(1)O6 octahedra,  a cornercorner with one As(2)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 42-49°. In the second As site, As(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form AsO4 tetrahedra that share corners with two equivalent K(1)O8 hexagonal bipyramids, corners with three equivalent Al(1)O6 octahedra, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-52°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Al(1), and one As(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Al(1), and one As(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one K(2), one Al(1), and one As(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one K(1), one As(1), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one K(2), one Al(1), and one As(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one K(1), one Al(1), and one As(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one K(2), one Al(1), and one As(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KAlAs2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.306
_cell_length_b   6.390
_cell_length_c   8.325
_cell_angle_alpha   96.799
_cell_angle_beta   104.578
_cell_angle_gamma   102.494
_symmetry_Int_Tables_number   1
_cell_volume   311.632
_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  0.000  0.000  0.500  1.0
  K  K1  1  0.000  0.000  0.000  1.0
  Al  Al2  1  0.625  0.311  0.772  1.0
  Al  Al3  1  0.375  0.689  0.228  1.0
  As  As4  1  0.175  0.470  0.812  1.0
  As  As5  1  0.825  0.530  0.188  1.0
  As  As6  1  0.512  0.756  0.664  1.0
  As  As7  1  0.488  0.244  0.336  1.0
  O  O8  1  0.906  0.313  0.723  1.0
  O  O9  1  0.094  0.687  0.277  1.0
  O  O10  1  0.338  0.289  0.816  1.0
  O  O11  1  0.662  0.711  0.184  1.0
  O  O12  1  0.218  0.649  0.990  1.0
  O  O13  1  0.782  0.351  0.010  1.0
  O  O14  1  0.222  0.637  0.655  1.0
  O  O15  1  0.778  0.363  0.345  1.0
  O  O16  1  0.414  0.990  0.221  1.0
  O  O17  1  0.586  0.010  0.779  1.0
  O  O18  1  0.459  0.248  0.533  1.0
  O  O19  1  0.541  0.752  0.467  1.0
  O  O20  1  0.320  0.381  0.220  1.0
  O  O21  1  0.680  0.619  0.780  1.0
[/CIF]
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The crystal structure described by KAlAs2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted KO8 hexagonal bipyramids that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, corners with four equivalent As(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 52°. In the second K site, K(2) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms. Al(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form AlO6 octahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid, corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share  a cornercorner with one K(1)O8 hexagonal bipyramid, corners with three equivalent Al(1)O6 octahedra,  a cornercorner with one As(2)O4 tetrahedra, and  an edgeedge with one K(1)O8 hexagonal bipyramid. The corner-sharing octahedral tilt angles range from 42-49°. In the second As site, As(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form AsO4 tetrahedra that share corners with two equivalent K(1)O8 hexagonal bipyramids, corners with three equivalent Al(1)O6 octahedra, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-52°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Al(1), and one As(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Al(1), and one As(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one K(2), one Al(1), and one As(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one K(1), one As(1), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one K(2), one Al(1), and one As(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one K(1), one Al(1), and one As(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one K(2), one Al(1), and one As(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KAlAs2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.306
_cell_length_b   6.390
_cell_length_c   8.325
_cell_angle_alpha   96.799
_cell_angle_beta   104.578
_cell_angle_gamma   102.494
_symmetry_Int_Tables_number   1
_cell_volume   311.632
_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  0.000  0.000  0.500  1.0
  K  K1  1  0.000  0.000  0.000  1.0
  Al  Al2  1  0.625  0.311  0.772  1.0
  Al  Al3  1  0.375  0.689  0.228  1.0
  As  As4  1  0.175  0.470  0.812  1.0
  As  As5  1  0.825  0.530  0.188  1.0
  As  As6  1  0.512  0.756  0.664  1.0
  As  As7  1  0.488  0.244  0.336  1.0
  O  O8  1  0.906  0.313  0.723  1.0
  O  O9  1  0.094  0.687  0.277  1.0
  O  O10  1  0.338  0.289  0.816  1.0
  O  O11  1  0.662  0.711  0.184  1.0
  O  O12  1  0.218  0.649  0.990  1.0
  O  O13  1  0.782  0.351  0.010  1.0
  O  O14  1  0.222  0.637  0.655  1.0
  O  O15  1  0.778  0.363  0.345  1.0
  O  O16  1  0.414  0.990  0.221  1.0
  O  O17  1  0.586  0.010  0.779  1.0
  O  O18  1  0.459  0.248  0.533  1.0
  O  O19  1  0.541  0.752  0.467  1.0
  O  O20  1  0.320  0.381  0.220  1.0
  O  O21  1  0.680  0.619  0.780  1.0
[/CIF]
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