The compound described by Mn2As2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MnO6 pentagonal pyramids that share corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and edges with three equivalent Mn(2)O6 octahedra. In the second Mn site, Mn(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MnO6 octahedra that share corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and edges with three equivalent Mn(1)O6 pentagonal pyramids. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form AsO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(1)O6 pentagonal pyramids, and  a cornercorner with one As(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-61°. In the second As site, As(2) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form AsO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(1)O6 pentagonal pyramids, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-61°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one As(1) and one As(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mn2As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.830
_cell_length_b   5.525
_cell_length_c   5.529
_cell_angle_alpha   104.896
_cell_angle_beta   97.733
_cell_angle_gamma   97.687
_symmetry_Int_Tables_number   1
_cell_volume   139.095
_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
  Mn  Mn0  1  0.503  0.697  0.306  1.0
  Mn  Mn1  1  0.505  0.311  0.691  1.0
  As  As2  1  0.909  0.229  0.235  1.0
  As  As3  1  0.099  0.768  0.774  1.0
  O  O4  1  0.714  0.082  0.405  1.0
  O  O5  1  0.720  0.385  0.068  1.0
  O  O6  1  0.288  0.935  0.617  1.0
  O  O7  1  0.294  0.598  0.920  1.0
  O  O8  1  0.227  0.401  0.394  1.0
  O  O9  1  0.781  0.610  0.602  1.0
  O  O10  1  0.005  0.967  0.036  1.0
[/CIF]
.
The compound described by Mn2As2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MnO6 pentagonal pyramids that share corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and edges with three equivalent Mn(2)O6 octahedra. In the second Mn site, Mn(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MnO6 octahedra that share corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and edges with three equivalent Mn(1)O6 pentagonal pyramids. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form AsO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(1)O6 pentagonal pyramids, and  a cornercorner with one As(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-61°. In the second As site, As(2) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form AsO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(1)O6 pentagonal pyramids, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-61°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one As(1) and one As(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mn2As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.830
_cell_length_b   5.525
_cell_length_c   5.529
_cell_angle_alpha   104.896
_cell_angle_beta   97.733
_cell_angle_gamma   97.687
_symmetry_Int_Tables_number   1
_cell_volume   139.095
_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
  Mn  Mn0  1  0.503  0.697  0.306  1.0
  Mn  Mn1  1  0.505  0.311  0.691  1.0
  As  As2  1  0.909  0.229  0.235  1.0
  As  As3  1  0.099  0.768  0.774  1.0
  O  O4  1  0.714  0.082  0.405  1.0
  O  O5  1  0.720  0.385  0.068  1.0
  O  O6  1  0.288  0.935  0.617  1.0
  O  O7  1  0.294  0.598  0.920  1.0
  O  O8  1  0.227  0.401  0.394  1.0
  O  O9  1  0.781  0.610  0.602  1.0
  O  O10  1  0.005  0.967  0.036  1.0
[/CIF]
.