The compound described by KMgNi2H3(SeO5)2 crystallizes in the triclinic P1 space group. K(1) is bonded in a 8-coordinate geometry to one Se(1), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(1) atoms. Mg(1) is bonded to one O(10), one O(3), one O(4), one O(8), and one O(9) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Ni(1)O5 square pyramid,  a cornercorner with one Ni(2)O5 square pyramid,  a cornercorner with one Se(2)O4 tetrahedra,  an edgeedge with one Ni(1)O5 square pyramid, and  an edgeedge with one Ni(2)O5 square pyramid. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(10), one O(6), one O(7), one O(8), and one O(9) atom to form distorted NiO5 square pyramids that share corners with two equivalent Se(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, edges with two equivalent Ni(2)O5 square pyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. In the second Ni site, Ni(2) is bonded to one O(10), one O(5), one O(7), one O(8), and one O(9) atom to form distorted NiO5 square pyramids that share corners with two equivalent Se(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, edges with two equivalent Ni(1)O5 square pyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. There are three inequivalent H sites. In the first H site, H(1) is bonded in a distorted bent 150 degrees geometry to one O(1) and one O(7) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(8) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(7) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to one K(1), one O(1), one O(3), and one O(4) atom. In the second Se site, Se(2) is bonded to one O(10), one O(2), one O(5), and one O(6) atom to form SeO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids, corners with two equivalent Ni(2)O5 square pyramids, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one H(1), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1) and one Se(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one K(1), one Mg(1), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one K(1), one Mg(1), and one Se(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one K(1), one Ni(2), and one Se(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one K(1), one Ni(1), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted tetrahedral geometry to one Ni(1), one Ni(2), one H(1), and one H(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Ni(2), and one H(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one Ni(2) atom. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(1), one Ni(2), and one Se(2) atom. is represented by the CIF file [CIF]
data_KMgNi2H3(SeO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.853
_cell_length_b   5.821
_cell_length_c   9.370
_cell_angle_alpha   74.597
_cell_angle_beta   74.224
_cell_angle_gamma   61.215
_symmetry_Int_Tables_number   1
_cell_volume   265.806
_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
  K  K0  1  0.468  0.473  0.520  1.0
  Mg  Mg1  1  0.026  0.025  0.123  1.0
  Ni  Ni2  1  0.030  0.560  0.953  1.0
  Ni  Ni3  1  0.559  0.034  0.954  1.0
  H  H4  1  0.803  0.798  0.667  1.0
  H  H5  1  0.274  0.287  0.188  1.0
  H  H6  1  0.623  0.621  0.854  1.0
  Se  Se7  1  0.835  0.831  0.396  1.0
  Se  Se8  1  0.077  0.077  0.756  1.0
  O  O9  1  0.886  0.875  0.565  1.0
  O  O10  1  0.194  0.192  0.588  1.0
  O  O11  1  0.153  0.714  0.301  1.0
  O  O12  1  0.722  0.151  0.305  1.0
  O  O13  1  0.742  0.227  0.782  1.0
  O  O14  1  0.225  0.741  0.782  1.0
  O  O15  1  0.721  0.722  0.842  1.0
  O  O16  1  0.241  0.245  0.104  1.0
  O  O17  1  0.855  0.859  0.060  1.0
  O  O18  1  0.163  0.164  0.890  1.0
[/CIF]
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The compound described by KMgNi2H3(SeO5)2 crystallizes in the triclinic P1 space group. K(1) is bonded in a 8-coordinate geometry to one Se(1), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(1) atoms. Mg(1) is bonded to one O(10), one O(3), one O(4), one O(8), and one O(9) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Ni(1)O5 square pyramid,  a cornercorner with one Ni(2)O5 square pyramid,  a cornercorner with one Se(2)O4 tetrahedra,  an edgeedge with one Ni(1)O5 square pyramid, and  an edgeedge with one Ni(2)O5 square pyramid. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(10), one O(6), one O(7), one O(8), and one O(9) atom to form distorted NiO5 square pyramids that share corners with two equivalent Se(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, edges with two equivalent Ni(2)O5 square pyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. In the second Ni site, Ni(2) is bonded to one O(10), one O(5), one O(7), one O(8), and one O(9) atom to form distorted NiO5 square pyramids that share corners with two equivalent Se(2)O4 tetrahedra,  a cornercorner with one Mg(1)O5 trigonal bipyramid, edges with two equivalent Ni(1)O5 square pyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. There are three inequivalent H sites. In the first H site, H(1) is bonded in a distorted bent 150 degrees geometry to one O(1) and one O(7) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(8) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(7) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to one K(1), one O(1), one O(3), and one O(4) atom. In the second Se site, Se(2) is bonded to one O(10), one O(2), one O(5), and one O(6) atom to form SeO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids, corners with two equivalent Ni(2)O5 square pyramids, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one H(1), and one Se(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1) and one Se(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one K(1), one Mg(1), and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one K(1), one Mg(1), and one Se(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one K(1), one Ni(2), and one Se(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one K(1), one Ni(1), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted tetrahedral geometry to one Ni(1), one Ni(2), one H(1), and one H(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Mg(1), one Ni(1), one Ni(2), and one H(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one Ni(2) atom. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(1), one Ni(2), and one Se(2) atom. is represented by the CIF file [CIF]
data_KMgNi2H3(SeO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.853
_cell_length_b   5.821
_cell_length_c   9.370
_cell_angle_alpha   74.597
_cell_angle_beta   74.224
_cell_angle_gamma   61.215
_symmetry_Int_Tables_number   1
_cell_volume   265.806
_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
  K  K0  1  0.468  0.473  0.520  1.0
  Mg  Mg1  1  0.026  0.025  0.123  1.0
  Ni  Ni2  1  0.030  0.560  0.953  1.0
  Ni  Ni3  1  0.559  0.034  0.954  1.0
  H  H4  1  0.803  0.798  0.667  1.0
  H  H5  1  0.274  0.287  0.188  1.0
  H  H6  1  0.623  0.621  0.854  1.0
  Se  Se7  1  0.835  0.831  0.396  1.0
  Se  Se8  1  0.077  0.077  0.756  1.0
  O  O9  1  0.886  0.875  0.565  1.0
  O  O10  1  0.194  0.192  0.588  1.0
  O  O11  1  0.153  0.714  0.301  1.0
  O  O12  1  0.722  0.151  0.305  1.0
  O  O13  1  0.742  0.227  0.782  1.0
  O  O14  1  0.225  0.741  0.782  1.0
  O  O15  1  0.721  0.722  0.842  1.0
  O  O16  1  0.241  0.245  0.104  1.0
  O  O17  1  0.855  0.859  0.060  1.0
  O  O18  1  0.163  0.164  0.890  1.0
[/CIF]
.