The crystal structure described by Nd2As4O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 9-coordinate geometry to one O(3), one O(6), one O(7), one O(8), one O(9), two equivalent O(1), and two equivalent O(4) atoms. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(6), one O(9), two equivalent O(2), and two equivalent O(7) atoms. There are four inequivalent As sites. In the first As site, As(1) is bonded in a distorted T-shaped geometry to one O(5), one O(8), and one O(9) atom. In the second As site, As(2) is bonded in a distorted trigonal non-coplanar geometry to one O(3), one O(5), and one O(8) atom. In the third As site, As(3) is bonded in a distorted T-shaped geometry to one O(1), one O(2), and one O(7) atom. In the fourth As site, As(4) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(4), and one O(6) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Nd(1), one As(3), and one As(4) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Nd(2) and one As(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one As(2) atom. In the fourth O site, O(4) is bonded to one Nd(2), two equivalent Nd(1), and one As(4) atom to form a mixture of distorted corner and edge-sharing ONd3As tetrahedra. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one As(1) and one As(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one As(4) atom. In the seventh O site, O(7) is bonded to one Nd(1), two equivalent Nd(2), and one As(3) atom to form a mixture of distorted corner and edge-sharing ONd3As tetrahedra. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Nd(1), one As(1), and one As(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one As(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Nd2As4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.902
_cell_length_b   7.671
_cell_length_c   9.615
_cell_angle_alpha   96.438
_cell_angle_beta   103.766
_cell_angle_gamma   104.510
_symmetry_Int_Tables_number   1
_cell_volume   470.662
_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
  Nd  Nd0  1  0.750  0.943  0.120  1.0
  Nd  Nd1  1  0.779  0.468  0.095  1.0
  Nd  Nd2  1  0.250  0.057  0.880  1.0
  Nd  Nd3  1  0.221  0.532  0.905  1.0
  As  As4  1  0.824  0.227  0.441  1.0
  As  As5  1  0.321  0.239  0.579  1.0
  As  As6  1  0.679  0.761  0.421  1.0
  As  As7  1  0.176  0.773  0.559  1.0
  As  As8  1  0.692  0.649  0.792  1.0
  As  As9  1  0.308  0.351  0.208  1.0
  As  As10  1  0.251  0.922  0.215  1.0
  As  As11  1  0.749  0.078  0.785  1.0
  O  O12  1  0.862  0.896  0.855  1.0
  O  O13  1  0.127  0.457  0.129  1.0
  O  O14  1  0.632  0.665  0.240  1.0
  O  O15  1  0.658  0.131  0.938  1.0
  O  O16  1  0.104  0.316  0.492  1.0
  O  O17  1  0.873  0.543  0.871  1.0
  O  O18  1  0.999  0.223  0.826  1.0
  O  O19  1  0.138  0.104  0.145  1.0
  O  O20  1  0.592  0.667  0.946  1.0
  O  O21  1  0.817  0.986  0.388  1.0
  O  O22  1  0.368  0.335  0.760  1.0
  O  O23  1  0.001  0.777  0.174  1.0
  O  O24  1  0.226  0.750  0.741  1.0
  O  O25  1  0.408  0.333  0.054  1.0
  O  O26  1  0.183  0.014  0.612  1.0
  O  O27  1  0.342  0.869  0.062  1.0
  O  O28  1  0.774  0.250  0.259  1.0
  O  O29  1  0.896  0.684  0.508  1.0
[/CIF]
.
The crystal structure described by Nd2As4O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 9-coordinate geometry to one O(3), one O(6), one O(7), one O(8), one O(9), two equivalent O(1), and two equivalent O(4) atoms. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(6), one O(9), two equivalent O(2), and two equivalent O(7) atoms. There are four inequivalent As sites. In the first As site, As(1) is bonded in a distorted T-shaped geometry to one O(5), one O(8), and one O(9) atom. In the second As site, As(2) is bonded in a distorted trigonal non-coplanar geometry to one O(3), one O(5), and one O(8) atom. In the third As site, As(3) is bonded in a distorted T-shaped geometry to one O(1), one O(2), and one O(7) atom. In the fourth As site, As(4) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(4), and one O(6) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Nd(1), one As(3), and one As(4) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Nd(2) and one As(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one As(2) atom. In the fourth O site, O(4) is bonded to one Nd(2), two equivalent Nd(1), and one As(4) atom to form a mixture of distorted corner and edge-sharing ONd3As tetrahedra. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one As(1) and one As(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one As(4) atom. In the seventh O site, O(7) is bonded to one Nd(1), two equivalent Nd(2), and one As(3) atom to form a mixture of distorted corner and edge-sharing ONd3As tetrahedra. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Nd(1), one As(1), and one As(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Nd(1), one Nd(2), and one As(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Nd2As4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.902
_cell_length_b   7.671
_cell_length_c   9.615
_cell_angle_alpha   96.438
_cell_angle_beta   103.766
_cell_angle_gamma   104.510
_symmetry_Int_Tables_number   1
_cell_volume   470.662
_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
  Nd  Nd0  1  0.750  0.943  0.120  1.0
  Nd  Nd1  1  0.779  0.468  0.095  1.0
  Nd  Nd2  1  0.250  0.057  0.880  1.0
  Nd  Nd3  1  0.221  0.532  0.905  1.0
  As  As4  1  0.824  0.227  0.441  1.0
  As  As5  1  0.321  0.239  0.579  1.0
  As  As6  1  0.679  0.761  0.421  1.0
  As  As7  1  0.176  0.773  0.559  1.0
  As  As8  1  0.692  0.649  0.792  1.0
  As  As9  1  0.308  0.351  0.208  1.0
  As  As10  1  0.251  0.922  0.215  1.0
  As  As11  1  0.749  0.078  0.785  1.0
  O  O12  1  0.862  0.896  0.855  1.0
  O  O13  1  0.127  0.457  0.129  1.0
  O  O14  1  0.632  0.665  0.240  1.0
  O  O15  1  0.658  0.131  0.938  1.0
  O  O16  1  0.104  0.316  0.492  1.0
  O  O17  1  0.873  0.543  0.871  1.0
  O  O18  1  0.999  0.223  0.826  1.0
  O  O19  1  0.138  0.104  0.145  1.0
  O  O20  1  0.592  0.667  0.946  1.0
  O  O21  1  0.817  0.986  0.388  1.0
  O  O22  1  0.368  0.335  0.760  1.0
  O  O23  1  0.001  0.777  0.174  1.0
  O  O24  1  0.226  0.750  0.741  1.0
  O  O25  1  0.408  0.333  0.054  1.0
  O  O26  1  0.183  0.014  0.612  1.0
  O  O27  1  0.342  0.869  0.062  1.0
  O  O28  1  0.774  0.250  0.259  1.0
  O  O29  1  0.896  0.684  0.508  1.0
[/CIF]
.