The material described by MgSnAs2O7 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(1), one O(5), one O(6), one O(7), and two equivalent O(3) atoms to form distorted MgO6 pentagonal pyramids that share corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. Sn(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(7) atom. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form AsO4 tetrahedra that share corners with three equivalent Mg(1)O6 pentagonal pyramids and  a cornercorner with one As(2)O4 tetrahedra. In the second As site, As(2) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form AsO4 tetrahedra that share corners with three equivalent Mg(1)O6 pentagonal pyramids and  a cornercorner with one As(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Sn(1), and one As(2) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Mg(1), one Sn(1), and one As(1) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Sn(1), and one As(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Sn(1), and one As(2) atom. In the fifth O site, O(2) is bonded in a bent 150 degrees geometry to one Sn(1) and one As(1) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one As(1) atom. In the seventh O site, O(4) is bonded in a distorted bent 120 degrees geometry to one As(1) and one As(2) atom. is represented by the CIF card [CIF]
data_MgSnAs2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.329
_cell_length_b   7.612
_cell_length_c   9.999
_cell_angle_alpha   61.574
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   624.415
_cell_formula_units_Z   4
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
  Mg  Mg0  1  0.062  0.732  0.901  1.0
  Mg  Mg1  1  0.562  0.268  0.599  1.0
  Mg  Mg2  1  0.938  0.268  0.099  1.0
  Mg  Mg3  1  0.438  0.732  0.401  1.0
  Sn  Sn4  1  0.960  0.231  0.629  1.0
  Sn  Sn5  1  0.460  0.769  0.871  1.0
  Sn  Sn6  1  0.040  0.769  0.371  1.0
  Sn  Sn7  1  0.540  0.231  0.129  1.0
  As  As8  1  0.780  0.570  0.751  1.0
  As  As9  1  0.280  0.430  0.749  1.0
  As  As10  1  0.220  0.430  0.249  1.0
  As  As11  1  0.720  0.570  0.251  1.0
  As  As12  1  0.745  0.005  0.941  1.0
  As  As13  1  0.245  0.995  0.559  1.0
  As  As14  1  0.255  0.995  0.059  1.0
  As  As15  1  0.755  0.005  0.441  1.0
  O  O16  1  0.775  0.136  0.036  1.0
  O  O17  1  0.275  0.864  0.464  1.0
  O  O18  1  0.225  0.864  0.964  1.0
  O  O19  1  0.725  0.136  0.536  1.0
  O  O20  1  0.613  0.635  0.775  1.0
  O  O21  1  0.113  0.365  0.725  1.0
  O  O22  1  0.387  0.365  0.225  1.0
  O  O23  1  0.887  0.635  0.275  1.0
  O  O24  1  0.905  0.540  0.888  1.0
  O  O25  1  0.405  0.460  0.612  1.0
  O  O26  1  0.095  0.460  0.112  1.0
  O  O27  1  0.595  0.540  0.388  1.0
  O  O28  1  0.840  0.776  0.577  1.0
  O  O29  1  0.340  0.224  0.923  1.0
  O  O30  1  0.160  0.224  0.423  1.0
  O  O31  1  0.660  0.776  0.077  1.0
  O  O32  1  0.899  0.064  0.321  1.0
  O  O33  1  0.399  0.936  0.179  1.0
  O  O34  1  0.101  0.936  0.679  1.0
  O  O35  1  0.601  0.064  0.821  1.0
  O  O36  1  0.722  0.380  0.206  1.0
  O  O37  1  0.222  0.620  0.294  1.0
  O  O38  1  0.278  0.620  0.794  1.0
  O  O39  1  0.778  0.380  0.706  1.0
  O  O40  1  0.601  0.960  0.367  1.0
  O  O41  1  0.101  0.040  0.133  1.0
  O  O42  1  0.399  0.040  0.633  1.0
  O  O43  1  0.899  0.960  0.867  1.0
[/CIF]
.
The material described by MgSnAs2O7 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(1), one O(5), one O(6), one O(7), and two equivalent O(3) atoms to form distorted MgO6 pentagonal pyramids that share corners with three equivalent As(1)O4 tetrahedra, corners with three equivalent As(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. Sn(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(7) atom. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form AsO4 tetrahedra that share corners with three equivalent Mg(1)O6 pentagonal pyramids and  a cornercorner with one As(2)O4 tetrahedra. In the second As site, As(2) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form AsO4 tetrahedra that share corners with three equivalent Mg(1)O6 pentagonal pyramids and  a cornercorner with one As(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Sn(1), and one As(2) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Mg(1), one Sn(1), and one As(1) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Sn(1), and one As(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Sn(1), and one As(2) atom. In the fifth O site, O(2) is bonded in a bent 150 degrees geometry to one Sn(1) and one As(1) atom. In the sixth O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one As(1) atom. In the seventh O site, O(4) is bonded in a distorted bent 120 degrees geometry to one As(1) and one As(2) atom. is represented by the CIF card [CIF]
data_MgSnAs2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.329
_cell_length_b   7.612
_cell_length_c   9.999
_cell_angle_alpha   61.574
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   624.415
_cell_formula_units_Z   4
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
  Mg  Mg0  1  0.062  0.732  0.901  1.0
  Mg  Mg1  1  0.562  0.268  0.599  1.0
  Mg  Mg2  1  0.938  0.268  0.099  1.0
  Mg  Mg3  1  0.438  0.732  0.401  1.0
  Sn  Sn4  1  0.960  0.231  0.629  1.0
  Sn  Sn5  1  0.460  0.769  0.871  1.0
  Sn  Sn6  1  0.040  0.769  0.371  1.0
  Sn  Sn7  1  0.540  0.231  0.129  1.0
  As  As8  1  0.780  0.570  0.751  1.0
  As  As9  1  0.280  0.430  0.749  1.0
  As  As10  1  0.220  0.430  0.249  1.0
  As  As11  1  0.720  0.570  0.251  1.0
  As  As12  1  0.745  0.005  0.941  1.0
  As  As13  1  0.245  0.995  0.559  1.0
  As  As14  1  0.255  0.995  0.059  1.0
  As  As15  1  0.755  0.005  0.441  1.0
  O  O16  1  0.775  0.136  0.036  1.0
  O  O17  1  0.275  0.864  0.464  1.0
  O  O18  1  0.225  0.864  0.964  1.0
  O  O19  1  0.725  0.136  0.536  1.0
  O  O20  1  0.613  0.635  0.775  1.0
  O  O21  1  0.113  0.365  0.725  1.0
  O  O22  1  0.387  0.365  0.225  1.0
  O  O23  1  0.887  0.635  0.275  1.0
  O  O24  1  0.905  0.540  0.888  1.0
  O  O25  1  0.405  0.460  0.612  1.0
  O  O26  1  0.095  0.460  0.112  1.0
  O  O27  1  0.595  0.540  0.388  1.0
  O  O28  1  0.840  0.776  0.577  1.0
  O  O29  1  0.340  0.224  0.923  1.0
  O  O30  1  0.160  0.224  0.423  1.0
  O  O31  1  0.660  0.776  0.077  1.0
  O  O32  1  0.899  0.064  0.321  1.0
  O  O33  1  0.399  0.936  0.179  1.0
  O  O34  1  0.101  0.936  0.679  1.0
  O  O35  1  0.601  0.064  0.821  1.0
  O  O36  1  0.722  0.380  0.206  1.0
  O  O37  1  0.222  0.620  0.294  1.0
  O  O38  1  0.278  0.620  0.794  1.0
  O  O39  1  0.778  0.380  0.706  1.0
  O  O40  1  0.601  0.960  0.367  1.0
  O  O41  1  0.101  0.040  0.133  1.0
  O  O42  1  0.399  0.040  0.633  1.0
  O  O43  1  0.899  0.960  0.867  1.0
[/CIF]
.