The compound described by Mg3(AlN2)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent N(2) and three equivalent N(1) atoms to form distorted MgN5 trigonal bipyramids that share corners with four equivalent Mg(2)N6 octahedra, corners with six equivalent Al(1)N4 tetrahedra, corners with two equivalent Mg(1)N5 trigonal bipyramids, edges with two equivalent Al(1)N4 tetrahedra, edges with three equivalent Mg(1)N5 trigonal bipyramids, and  a faceface with one Mg(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 36-56°. In the second Mg site, Mg(2) is bonded to two equivalent N(1) and four equivalent N(2) atoms to form MgN6 octahedra that share corners with four equivalent Al(1)N4 tetrahedra, corners with eight equivalent Mg(1)N5 trigonal bipyramids, edges with two equivalent Mg(2)N6 octahedra, edges with four equivalent Al(1)N4 tetrahedra, and faces with two equivalent Mg(1)N5 trigonal bipyramids. Al(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form AlN4 tetrahedra that share corners with two equivalent Mg(2)N6 octahedra, corners with two equivalent Al(1)N4 tetrahedra, corners with six equivalent Mg(1)N5 trigonal bipyramids, edges with two equivalent Mg(2)N6 octahedra,  an edgeedge with one Al(1)N4 tetrahedra, and edges with two equivalent Mg(1)N5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 25-56°. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Mg(2), three equivalent Mg(1), and two equivalent Al(1) atoms to form a mixture of distorted corner, face, and edge-sharing NMg4Al2 pentagonal pyramids. In the second N site, N(2) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_Mg3(AlN2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.189
_cell_length_b   7.271
_cell_length_c   5.490
_cell_angle_alpha   90.000
_cell_angle_beta   89.745
_cell_angle_gamma   125.971
_symmetry_Int_Tables_number   1
_cell_volume   199.950
_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
  Mg  Mg0  1  0.225  0.988  0.969  1.0
  Mg  Mg1  1  0.775  0.763  0.531  1.0
  Mg  Mg2  1  0.775  0.012  0.031  1.0
  Mg  Mg3  1  0.225  0.237  0.469  1.0
  Mg  Mg4  1  0.000  0.598  0.750  1.0
  Mg  Mg5  1  0.000  0.402  0.250  1.0
  Al  Al6  1  0.620  0.186  0.607  1.0
  Al  Al7  1  0.380  0.566  0.893  1.0
  Al  Al8  1  0.380  0.814  0.393  1.0
  Al  Al9  1  0.620  0.434  0.107  1.0
  N  N10  1  0.241  0.957  0.566  1.0
  N  N11  1  0.759  0.716  0.934  1.0
  N  N12  1  0.759  0.043  0.434  1.0
  N  N13  1  0.241  0.284  0.066  1.0
  N  N14  1  0.717  0.267  0.933  1.0
  N  N15  1  0.283  0.550  0.567  1.0
  N  N16  1  0.283  0.733  0.067  1.0
  N  N17  1  0.717  0.450  0.433  1.0
[/CIF]
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The compound described by Mg3(AlN2)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent N(2) and three equivalent N(1) atoms to form distorted MgN5 trigonal bipyramids that share corners with four equivalent Mg(2)N6 octahedra, corners with six equivalent Al(1)N4 tetrahedra, corners with two equivalent Mg(1)N5 trigonal bipyramids, edges with two equivalent Al(1)N4 tetrahedra, edges with three equivalent Mg(1)N5 trigonal bipyramids, and  a faceface with one Mg(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 36-56°. In the second Mg site, Mg(2) is bonded to two equivalent N(1) and four equivalent N(2) atoms to form MgN6 octahedra that share corners with four equivalent Al(1)N4 tetrahedra, corners with eight equivalent Mg(1)N5 trigonal bipyramids, edges with two equivalent Mg(2)N6 octahedra, edges with four equivalent Al(1)N4 tetrahedra, and faces with two equivalent Mg(1)N5 trigonal bipyramids. Al(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form AlN4 tetrahedra that share corners with two equivalent Mg(2)N6 octahedra, corners with two equivalent Al(1)N4 tetrahedra, corners with six equivalent Mg(1)N5 trigonal bipyramids, edges with two equivalent Mg(2)N6 octahedra,  an edgeedge with one Al(1)N4 tetrahedra, and edges with two equivalent Mg(1)N5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 25-56°. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Mg(2), three equivalent Mg(1), and two equivalent Al(1) atoms to form a mixture of distorted corner, face, and edge-sharing NMg4Al2 pentagonal pyramids. In the second N site, N(2) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_Mg3(AlN2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.189
_cell_length_b   7.271
_cell_length_c   5.490
_cell_angle_alpha   90.000
_cell_angle_beta   89.745
_cell_angle_gamma   125.971
_symmetry_Int_Tables_number   1
_cell_volume   199.950
_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
  Mg  Mg0  1  0.225  0.988  0.969  1.0
  Mg  Mg1  1  0.775  0.763  0.531  1.0
  Mg  Mg2  1  0.775  0.012  0.031  1.0
  Mg  Mg3  1  0.225  0.237  0.469  1.0
  Mg  Mg4  1  0.000  0.598  0.750  1.0
  Mg  Mg5  1  0.000  0.402  0.250  1.0
  Al  Al6  1  0.620  0.186  0.607  1.0
  Al  Al7  1  0.380  0.566  0.893  1.0
  Al  Al8  1  0.380  0.814  0.393  1.0
  Al  Al9  1  0.620  0.434  0.107  1.0
  N  N10  1  0.241  0.957  0.566  1.0
  N  N11  1  0.759  0.716  0.934  1.0
  N  N12  1  0.759  0.043  0.434  1.0
  N  N13  1  0.241  0.284  0.066  1.0
  N  N14  1  0.717  0.267  0.933  1.0
  N  N15  1  0.283  0.550  0.567  1.0
  N  N16  1  0.283  0.733  0.067  1.0
  N  N17  1  0.717  0.450  0.433  1.0
[/CIF]
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