The material described by Mg5(SiN3)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent N(1) and two equivalent N(3) atoms to form distorted MgN4 trigonal pyramids that share corners with two equivalent Mg(2)N5 square pyramids, corners with four equivalent Si(1)N4 tetrahedra, and edges with two equivalent Mg(2)N5 square pyramids. In the second Mg site, Mg(2) is bonded to one N(1), two equivalent N(2), and two equivalent N(3) atoms to form distorted MgN5 square pyramids that share corners with three equivalent Si(1)N4 tetrahedra,  a cornercorner with one Mg(1)N4 trigonal pyramid, edges with two equivalent Mg(2)N5 square pyramids, edges with two equivalent Si(1)N4 tetrahedra, and  an edgeedge with one Mg(1)N4 trigonal pyramid. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one N(2), two equivalent N(1), and two equivalent N(3) atoms. Si(1) is bonded to one N(1), one N(3), and two equivalent N(2) atoms to form SiN4 tetrahedra that share corners with three equivalent Mg(2)N5 square pyramids, corners with two equivalent Mg(1)N4 trigonal pyramids, edges with two equivalent Mg(2)N5 square pyramids, and  an edgeedge with one Si(1)N4 tetrahedra. There are three inequivalent N sites. In the first N site, N(2) is bonded in a 5-coordinate geometry to one Mg(3), two equivalent Mg(2), and two equivalent Si(1) atoms. In the second N site, N(3) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), and one Si(1) atom to form distorted NMg5Si octahedra that share corners with five equivalent N(1)Mg4Si trigonal bipyramids,  an edgeedge with one N(3)Mg5Si octahedra, edges with two equivalent N(1)Mg4Si trigonal bipyramids, and  a faceface with one N(3)Mg5Si octahedra. In the third N site, N(1) is bonded to one Mg(1), one Mg(2), two equivalent Mg(3), and one Si(1) atom to form distorted NMg4Si trigonal bipyramids that share corners with five equivalent N(3)Mg5Si octahedra, corners with three equivalent N(1)Mg4Si trigonal bipyramids, and edges with two equivalent N(3)Mg5Si octahedra. The corner-sharing octahedral tilt angles range from 4-72°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg5(SiN3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.402
_cell_length_b   5.307
_cell_length_c   12.110
_cell_angle_alpha   90.000
_cell_angle_beta   94.136
_cell_angle_gamma   119.420
_symmetry_Int_Tables_number   1
_cell_volume   301.333
_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  0.000  0.390  0.750  1.0
  Mg  Mg1  1  0.000  0.610  0.250  1.0
  Mg  Mg2  1  0.193  0.853  0.023  1.0
  Mg  Mg3  1  0.807  0.660  0.477  1.0
  Mg  Mg4  1  0.807  0.147  0.977  1.0
  Mg  Mg5  1  0.193  0.340  0.523  1.0
  Mg  Mg6  1  0.291  0.069  0.719  1.0
  Mg  Mg7  1  0.709  0.778  0.781  1.0
  Mg  Mg8  1  0.709  0.931  0.281  1.0
  Mg  Mg9  1  0.291  0.222  0.219  1.0
  Si  Si10  1  0.573  0.931  0.586  1.0
  Si  Si11  1  0.427  0.359  0.914  1.0
  Si  Si12  1  0.427  0.069  0.414  1.0
  Si  Si13  1  0.573  0.641  0.086  1.0
  N  N14  1  0.336  0.710  0.677  1.0
  N  N15  1  0.664  0.374  0.823  1.0
  N  N16  1  0.664  0.290  0.323  1.0
  N  N17  1  0.336  0.626  0.177  1.0
  N  N18  1  0.538  0.243  0.550  1.0
  N  N19  1  0.462  0.705  0.950  1.0
  N  N20  1  0.462  0.757  0.450  1.0
  N  N21  1  0.538  0.295  0.050  1.0
  N  N22  1  0.917  0.023  0.630  1.0
  N  N23  1  0.083  0.106  0.870  1.0
  N  N24  1  0.083  0.977  0.370  1.0
  N  N25  1  0.917  0.894  0.130  1.0
[/CIF]
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The material described by Mg5(SiN3)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent N(1) and two equivalent N(3) atoms to form distorted MgN4 trigonal pyramids that share corners with two equivalent Mg(2)N5 square pyramids, corners with four equivalent Si(1)N4 tetrahedra, and edges with two equivalent Mg(2)N5 square pyramids. In the second Mg site, Mg(2) is bonded to one N(1), two equivalent N(2), and two equivalent N(3) atoms to form distorted MgN5 square pyramids that share corners with three equivalent Si(1)N4 tetrahedra,  a cornercorner with one Mg(1)N4 trigonal pyramid, edges with two equivalent Mg(2)N5 square pyramids, edges with two equivalent Si(1)N4 tetrahedra, and  an edgeedge with one Mg(1)N4 trigonal pyramid. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one N(2), two equivalent N(1), and two equivalent N(3) atoms. Si(1) is bonded to one N(1), one N(3), and two equivalent N(2) atoms to form SiN4 tetrahedra that share corners with three equivalent Mg(2)N5 square pyramids, corners with two equivalent Mg(1)N4 trigonal pyramids, edges with two equivalent Mg(2)N5 square pyramids, and  an edgeedge with one Si(1)N4 tetrahedra. There are three inequivalent N sites. In the first N site, N(2) is bonded in a 5-coordinate geometry to one Mg(3), two equivalent Mg(2), and two equivalent Si(1) atoms. In the second N site, N(3) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), and one Si(1) atom to form distorted NMg5Si octahedra that share corners with five equivalent N(1)Mg4Si trigonal bipyramids,  an edgeedge with one N(3)Mg5Si octahedra, edges with two equivalent N(1)Mg4Si trigonal bipyramids, and  a faceface with one N(3)Mg5Si octahedra. In the third N site, N(1) is bonded to one Mg(1), one Mg(2), two equivalent Mg(3), and one Si(1) atom to form distorted NMg4Si trigonal bipyramids that share corners with five equivalent N(3)Mg5Si octahedra, corners with three equivalent N(1)Mg4Si trigonal bipyramids, and edges with two equivalent N(3)Mg5Si octahedra. The corner-sharing octahedral tilt angles range from 4-72°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg5(SiN3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.402
_cell_length_b   5.307
_cell_length_c   12.110
_cell_angle_alpha   90.000
_cell_angle_beta   94.136
_cell_angle_gamma   119.420
_symmetry_Int_Tables_number   1
_cell_volume   301.333
_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  0.000  0.390  0.750  1.0
  Mg  Mg1  1  0.000  0.610  0.250  1.0
  Mg  Mg2  1  0.193  0.853  0.023  1.0
  Mg  Mg3  1  0.807  0.660  0.477  1.0
  Mg  Mg4  1  0.807  0.147  0.977  1.0
  Mg  Mg5  1  0.193  0.340  0.523  1.0
  Mg  Mg6  1  0.291  0.069  0.719  1.0
  Mg  Mg7  1  0.709  0.778  0.781  1.0
  Mg  Mg8  1  0.709  0.931  0.281  1.0
  Mg  Mg9  1  0.291  0.222  0.219  1.0
  Si  Si10  1  0.573  0.931  0.586  1.0
  Si  Si11  1  0.427  0.359  0.914  1.0
  Si  Si12  1  0.427  0.069  0.414  1.0
  Si  Si13  1  0.573  0.641  0.086  1.0
  N  N14  1  0.336  0.710  0.677  1.0
  N  N15  1  0.664  0.374  0.823  1.0
  N  N16  1  0.664  0.290  0.323  1.0
  N  N17  1  0.336  0.626  0.177  1.0
  N  N18  1  0.538  0.243  0.550  1.0
  N  N19  1  0.462  0.705  0.950  1.0
  N  N20  1  0.462  0.757  0.450  1.0
  N  N21  1  0.538  0.295  0.050  1.0
  N  N22  1  0.917  0.023  0.630  1.0
  N  N23  1  0.083  0.106  0.870  1.0
  N  N24  1  0.083  0.977  0.370  1.0
  N  N25  1  0.917  0.894  0.130  1.0
[/CIF]
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