The compound described by Mg4Al3(HO)17 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with two equivalent Al(1)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(3), one O(6), two equivalent O(4), and two equivalent O(5) atoms to form edge-sharing MgO6 octahedra. In the third Mg site, Mg(3) is bonded to one O(5), one O(8), two equivalent O(6), and two equivalent O(7) atoms to form edge-sharing MgO6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(11), one O(7), two equivalent O(8), and two equivalent O(9) atoms to form MgO6 octahedra that share edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, and edges with two equivalent Al(2)O6 octahedra. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(15), one O(2), two equivalent O(1), and two equivalent O(17) atoms to form AlO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the second Al site, Al(2) is bonded to one O(14), one O(9), two equivalent O(11), and two equivalent O(12) atoms to form AlO6 octahedra that share edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the third Al site, Al(3) is bonded to one O(12), one O(17), two equivalent O(14), and two equivalent O(15) atoms to form edge-sharing AlO6 octahedra. There are seventeen inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(3) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(4) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(5) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(6) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(7) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(10) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(8) atom. In the tenth H site, H(10) is bonded in a single-bond geometry to one O(9) atom. In the eleventh H site, H(11) is bonded in a single-bond geometry to one O(13) atom. In the twelfth H site, H(12) is bonded in a linear geometry to one O(10) and one O(11) atom. In the thirteenth H site, H(13) is bonded in a distorted linear geometry to one O(12) and one O(13) atom. In the fourteenth H site, H(14) is bonded in a single-bond geometry to one O(16) atom. In the fifteenth H site, H(15) is bonded in a linear geometry to one O(13) and one O(14) atom. In the sixteenth H site, H(16) is bonded in a distorted single-bond geometry to one O(15) atom. In the seventeenth H site, H(17) is bonded in a distorted linear geometry to one O(16) and one O(17) atom. There are seventeen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Al(1), and one H(1) atom. In the second O site, O(2) is bonded to two equivalent Mg(1), one Al(1), and one H(2) atom to form distorted OMg2AlH tetrahedra that share corners with two equivalent O(17)Al3H tetrahedra and corners with two equivalent O(2)Mg2AlH tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(2), two equivalent Mg(1), and one H(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Mg(2), and one H(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Mg(3), two equivalent Mg(2), and one H(5) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Mg(2), two equivalent Mg(3), and one H(6) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Mg(4), two equivalent Mg(3), and one H(7) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Mg(3), two equivalent Mg(4), and one H(9) atom. In the ninth O site, O(9) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(4), one Al(2), and one H(10) atom. In the tenth O site, O(10) is bonded in a water-like geometry to one H(12) and one H(8) atom. In the eleventh O site, O(11) is bonded to one Mg(4), two equivalent Al(2), and one H(12) atom to form distorted OMgAl2H trigonal pyramids that share corners with two equivalent O(14)Al3H tetrahedra and corners with two equivalent O(11)MgAl2H trigonal pyramids. In the twelfth O site, O(12) is bonded in a distorted rectangular see-saw-like geometry to one Al(3), two equivalent Al(2), and one H(13) atom. In the thirteenth O site, O(13) is bonded in a distorted water-like geometry to one H(11), one H(13), and one H(15) atom. In the fourteenth O site, O(14) is bonded to one Al(2), two equivalent Al(3), and one H(15) atom to form OAl3H tetrahedra that share corners with two equivalent O(14)Al3H tetrahedra, corners with two equivalent O(17)Al3H tetrahedra, and corners with two equivalent O(11)MgAl2H trigonal pyramids. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one Al(1), two equivalent Al(3), and one H(16) atom. In the sixteenth O site, O(16) is bonded in a distorted water-like geometry to one H(14) and one H(17) atom. In the seventeenth O site, O(17) is bonded to one Al(3), two equivalent Al(1), and one H(17) atom to form OAl3H tetrahedra that share corners with two equivalent O(14)Al3H tetrahedra, corners with two equivalent O(17)Al3H tetrahedra, and corners with two equivalent O(2)Mg2AlH tetrahedra. is represented by the CIF card [CIF]
data_Mg4Al3(HO)17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.036
_cell_length_b   7.173
_cell_length_c   18.564
_cell_angle_alpha   95.519
_cell_angle_beta   94.518
_cell_angle_gamma   101.953
_symmetry_Int_Tables_number   1
_cell_volume   391.658
_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
  Mg  Mg0  1  0.569  0.003  0.137  1.0
  Mg  Mg1  1  0.142  1.000  0.284  1.0
  Mg  Mg2  1  0.717  0.001  0.432  1.0
  Mg  Mg3  1  0.290  0.998  0.578  1.0
  Al  Al4  1  0.985  0.997  0.987  1.0
  Al  Al5  1  0.855  0.987  0.716  1.0
  Al  Al6  1  0.417  0.992  0.852  1.0
  H  H7  1  0.654  0.287  0.037  1.0
  H  H8  1  0.883  0.725  0.056  1.0
  H  H9  1  0.243  0.288  0.202  1.0
  H  H10  1  0.468  0.711  0.224  1.0
  H  H11  1  0.818  0.290  0.351  1.0
  H  H12  1  0.044  0.713  0.375  1.0
  H  H13  1  0.377  0.291  0.500  1.0
  H  H14  1  0.503  0.506  0.616  1.0
  H  H15  1  0.595  0.711  0.525  1.0
  H  H16  1  0.984  0.287  0.640  1.0
  H  H17  1  0.046  0.515  0.747  1.0
  H  H18  1  0.226  0.663  0.642  1.0
  H  H19  1  0.548  0.289  0.776  1.0
  H  H20  1  0.635  0.509  0.892  1.0
  H  H21  1  0.794  0.660  0.788  1.0
  H  H22  1  0.128  0.296  0.918  1.0
  H  H23  1  0.388  0.648  0.934  1.0
  O  O24  1  0.590  0.150  0.041  1.0
  O  O25  1  0.966  0.863  0.071  1.0
  O  O26  1  0.169  0.150  0.190  1.0
  O  O27  1  0.537  0.848  0.224  1.0
  O  O28  1  0.744  0.152  0.338  1.0
  O  O29  1  0.114  0.850  0.373  1.0
  O  O30  1  0.318  0.153  0.487  1.0
  O  O31  1  0.691  0.847  0.521  1.0
  O  O32  1  0.889  0.147  0.639  1.0
  O  O33  1  0.191  0.524  0.614  1.0
  O  O34  1  0.275  0.862  0.675  1.0
  O  O35  1  0.445  0.147  0.774  1.0
  O  O36  1  0.791  0.516  0.776  1.0
  O  O37  1  0.837  0.875  0.807  1.0
  O  O38  1  0.012  0.152  0.909  1.0
  O  O39  1  0.463  0.515  0.934  1.0
  O  O40  1  0.400  0.875  0.940  1.0
[/CIF]
.
The compound described by Mg4Al3(HO)17 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with two equivalent Al(1)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(3), one O(6), two equivalent O(4), and two equivalent O(5) atoms to form edge-sharing MgO6 octahedra. In the third Mg site, Mg(3) is bonded to one O(5), one O(8), two equivalent O(6), and two equivalent O(7) atoms to form edge-sharing MgO6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(11), one O(7), two equivalent O(8), and two equivalent O(9) atoms to form MgO6 octahedra that share edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, and edges with two equivalent Al(2)O6 octahedra. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(15), one O(2), two equivalent O(1), and two equivalent O(17) atoms to form AlO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the second Al site, Al(2) is bonded to one O(14), one O(9), two equivalent O(11), and two equivalent O(12) atoms to form AlO6 octahedra that share edges with two equivalent Mg(4)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the third Al site, Al(3) is bonded to one O(12), one O(17), two equivalent O(14), and two equivalent O(15) atoms to form edge-sharing AlO6 octahedra. There are seventeen inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(3) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(4) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(5) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(6) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(7) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(10) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(8) atom. In the tenth H site, H(10) is bonded in a single-bond geometry to one O(9) atom. In the eleventh H site, H(11) is bonded in a single-bond geometry to one O(13) atom. In the twelfth H site, H(12) is bonded in a linear geometry to one O(10) and one O(11) atom. In the thirteenth H site, H(13) is bonded in a distorted linear geometry to one O(12) and one O(13) atom. In the fourteenth H site, H(14) is bonded in a single-bond geometry to one O(16) atom. In the fifteenth H site, H(15) is bonded in a linear geometry to one O(13) and one O(14) atom. In the sixteenth H site, H(16) is bonded in a distorted single-bond geometry to one O(15) atom. In the seventeenth H site, H(17) is bonded in a distorted linear geometry to one O(16) and one O(17) atom. There are seventeen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Al(1), and one H(1) atom. In the second O site, O(2) is bonded to two equivalent Mg(1), one Al(1), and one H(2) atom to form distorted OMg2AlH tetrahedra that share corners with two equivalent O(17)Al3H tetrahedra and corners with two equivalent O(2)Mg2AlH tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(2), two equivalent Mg(1), and one H(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Mg(2), and one H(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Mg(3), two equivalent Mg(2), and one H(5) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Mg(2), two equivalent Mg(3), and one H(6) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Mg(4), two equivalent Mg(3), and one H(7) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Mg(3), two equivalent Mg(4), and one H(9) atom. In the ninth O site, O(9) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(4), one Al(2), and one H(10) atom. In the tenth O site, O(10) is bonded in a water-like geometry to one H(12) and one H(8) atom. In the eleventh O site, O(11) is bonded to one Mg(4), two equivalent Al(2), and one H(12) atom to form distorted OMgAl2H trigonal pyramids that share corners with two equivalent O(14)Al3H tetrahedra and corners with two equivalent O(11)MgAl2H trigonal pyramids. In the twelfth O site, O(12) is bonded in a distorted rectangular see-saw-like geometry to one Al(3), two equivalent Al(2), and one H(13) atom. In the thirteenth O site, O(13) is bonded in a distorted water-like geometry to one H(11), one H(13), and one H(15) atom. In the fourteenth O site, O(14) is bonded to one Al(2), two equivalent Al(3), and one H(15) atom to form OAl3H tetrahedra that share corners with two equivalent O(14)Al3H tetrahedra, corners with two equivalent O(17)Al3H tetrahedra, and corners with two equivalent O(11)MgAl2H trigonal pyramids. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one Al(1), two equivalent Al(3), and one H(16) atom. In the sixteenth O site, O(16) is bonded in a distorted water-like geometry to one H(14) and one H(17) atom. In the seventeenth O site, O(17) is bonded to one Al(3), two equivalent Al(1), and one H(17) atom to form OAl3H tetrahedra that share corners with two equivalent O(14)Al3H tetrahedra, corners with two equivalent O(17)Al3H tetrahedra, and corners with two equivalent O(2)Mg2AlH tetrahedra. is represented by the CIF card [CIF]
data_Mg4Al3(HO)17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.036
_cell_length_b   7.173
_cell_length_c   18.564
_cell_angle_alpha   95.519
_cell_angle_beta   94.518
_cell_angle_gamma   101.953
_symmetry_Int_Tables_number   1
_cell_volume   391.658
_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
  Mg  Mg0  1  0.569  0.003  0.137  1.0
  Mg  Mg1  1  0.142  1.000  0.284  1.0
  Mg  Mg2  1  0.717  0.001  0.432  1.0
  Mg  Mg3  1  0.290  0.998  0.578  1.0
  Al  Al4  1  0.985  0.997  0.987  1.0
  Al  Al5  1  0.855  0.987  0.716  1.0
  Al  Al6  1  0.417  0.992  0.852  1.0
  H  H7  1  0.654  0.287  0.037  1.0
  H  H8  1  0.883  0.725  0.056  1.0
  H  H9  1  0.243  0.288  0.202  1.0
  H  H10  1  0.468  0.711  0.224  1.0
  H  H11  1  0.818  0.290  0.351  1.0
  H  H12  1  0.044  0.713  0.375  1.0
  H  H13  1  0.377  0.291  0.500  1.0
  H  H14  1  0.503  0.506  0.616  1.0
  H  H15  1  0.595  0.711  0.525  1.0
  H  H16  1  0.984  0.287  0.640  1.0
  H  H17  1  0.046  0.515  0.747  1.0
  H  H18  1  0.226  0.663  0.642  1.0
  H  H19  1  0.548  0.289  0.776  1.0
  H  H20  1  0.635  0.509  0.892  1.0
  H  H21  1  0.794  0.660  0.788  1.0
  H  H22  1  0.128  0.296  0.918  1.0
  H  H23  1  0.388  0.648  0.934  1.0
  O  O24  1  0.590  0.150  0.041  1.0
  O  O25  1  0.966  0.863  0.071  1.0
  O  O26  1  0.169  0.150  0.190  1.0
  O  O27  1  0.537  0.848  0.224  1.0
  O  O28  1  0.744  0.152  0.338  1.0
  O  O29  1  0.114  0.850  0.373  1.0
  O  O30  1  0.318  0.153  0.487  1.0
  O  O31  1  0.691  0.847  0.521  1.0
  O  O32  1  0.889  0.147  0.639  1.0
  O  O33  1  0.191  0.524  0.614  1.0
  O  O34  1  0.275  0.862  0.675  1.0
  O  O35  1  0.445  0.147  0.774  1.0
  O  O36  1  0.791  0.516  0.776  1.0
  O  O37  1  0.837  0.875  0.807  1.0
  O  O38  1  0.012  0.152  0.909  1.0
  O  O39  1  0.463  0.515  0.934  1.0
  O  O40  1  0.400  0.875  0.940  1.0
[/CIF]
.