The structure described by Si2N2O is Ilmenite-like structured and crystallizes in the monoclinic C2/c space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent N(2), two equivalent N(3), and two equivalent O(1) atoms to form a mixture of distorted edge, face, and corner-sharing SiN4O2 octahedra. The corner-sharing octahedral tilt angles range from 43-63°. In the second Si site, Si(2) is bonded to one N(2), one N(3), two equivalent N(1), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing SiN4O2 octahedra. The corner-sharing octahedral tilt angles range from 46-63°. In the third Si site, Si(3) is bonded to one N(2), one N(3), two equivalent N(1), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing SiN4O2 octahedra. The corner-sharing octahedral tilt angles range from 43-63°. There are three inequivalent N sites. In the first N site, N(1) is bonded to two equivalent Si(2) and two equivalent Si(3) atoms to form distorted NSi4 trigonal pyramids that share corners with two equivalent N(1)Si4 trigonal pyramids, corners with two equivalent N(2)Si4 trigonal pyramids, corners with two equivalent O(1)Si4 trigonal pyramids, corners with two equivalent O(2)Si4 trigonal pyramids,  an edgeedge with one N(1)Si4 trigonal pyramid,  an edgeedge with one N(2)Si4 trigonal pyramid,  an edgeedge with one O(1)Si4 trigonal pyramid, and  an edgeedge with one O(2)Si4 trigonal pyramid. In the second N site, N(2) is bonded to one Si(2), one Si(3), and two equivalent Si(1) atoms to form NSi4 trigonal pyramids that share corners with two equivalent N(1)Si4 trigonal pyramids, corners with two equivalent O(2)Si4 trigonal pyramids, corners with four equivalent O(1)Si4 trigonal pyramids,  an edgeedge with one N(1)Si4 trigonal pyramid,  an edgeedge with one N(2)Si4 trigonal pyramid, and  an edgeedge with one O(1)Si4 trigonal pyramid. In the third N site, N(3) is bonded in a see-saw-like geometry to one Si(2), one Si(3), and two equivalent Si(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Si(2), one Si(3), and two equivalent Si(1) atoms to form distorted OSi4 trigonal pyramids that share corners with two equivalent N(1)Si4 trigonal pyramids, corners with two equivalent O(2)Si4 trigonal pyramids, corners with four equivalent N(2)Si4 trigonal pyramids,  an edgeedge with one N(1)Si4 trigonal pyramid,  an edgeedge with one N(2)Si4 trigonal pyramid, and  an edgeedge with one O(1)Si4 trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Si(2) and two equivalent Si(3) atoms to form distorted OSi4 trigonal pyramids that share corners with four equivalent N(1)Si4 trigonal pyramids, corners with four equivalent N(2)Si4 trigonal pyramids, corners with four equivalent O(1)Si4 trigonal pyramids, and edges with two equivalent N(1)Si4 trigonal pyramids. is represented by the CIF card [CIF]
data_Si2N2O
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.708
_cell_length_b   4.708
_cell_length_c   12.796
_cell_angle_alpha   89.917
_cell_angle_beta   89.917
_cell_angle_gamma   59.548
_symmetry_Int_Tables_number   1
_cell_volume   244.484
_cell_formula_units_Z   6
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
  Si  Si0  1  0.315  0.328  0.520  1.0
  Si  Si1  1  0.672  0.685  0.980  1.0
  Si  Si2  1  0.685  0.672  0.480  1.0
  Si  Si3  1  0.328  0.315  0.020  1.0
  Si  Si4  1  0.313  0.332  0.814  1.0
  Si  Si5  1  0.668  0.687  0.686  1.0
  Si  Si6  1  0.687  0.668  0.186  1.0
  Si  Si7  1  0.332  0.313  0.314  1.0
  Si  Si8  1  0.999  0.004  0.853  1.0
  Si  Si9  1  0.996  0.001  0.647  1.0
  Si  Si10  1  0.001  0.996  0.147  1.0
  Si  Si11  1  0.004  0.999  0.353  1.0
  N  N12  1  0.994  0.709  0.752  1.0
  N  N13  1  0.341  0.020  0.417  1.0
  N  N14  1  0.980  0.659  0.083  1.0
  N  N15  1  0.291  0.006  0.748  1.0
  N  N16  1  0.006  0.291  0.248  1.0
  N  N17  1  0.709  0.994  0.252  1.0
  N  N18  1  0.953  0.371  0.585  1.0
  N  N19  1  0.629  0.047  0.915  1.0
  N  N20  1  0.047  0.629  0.415  1.0
  N  N21  1  0.371  0.953  0.085  1.0
  N  N22  1  0.020  0.341  0.917  1.0
  N  N23  1  0.659  0.980  0.583  1.0
  O  O24  1  0.655  0.333  0.418  1.0
  O  O25  1  0.667  0.345  0.082  1.0
  O  O26  1  0.345  0.667  0.582  1.0
  O  O27  1  0.668  0.332  0.750  1.0
  O  O28  1  0.332  0.668  0.250  1.0
  O  O29  1  0.333  0.655  0.918  1.0
[/CIF]
.
The structure described by Si2N2O is Ilmenite-like structured and crystallizes in the monoclinic C2/c space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent N(2), two equivalent N(3), and two equivalent O(1) atoms to form a mixture of distorted edge, face, and corner-sharing SiN4O2 octahedra. The corner-sharing octahedral tilt angles range from 43-63°. In the second Si site, Si(2) is bonded to one N(2), one N(3), two equivalent N(1), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing SiN4O2 octahedra. The corner-sharing octahedral tilt angles range from 46-63°. In the third Si site, Si(3) is bonded to one N(2), one N(3), two equivalent N(1), one O(1), and one O(2) atom to form a mixture of distorted edge, face, and corner-sharing SiN4O2 octahedra. The corner-sharing octahedral tilt angles range from 43-63°. There are three inequivalent N sites. In the first N site, N(1) is bonded to two equivalent Si(2) and two equivalent Si(3) atoms to form distorted NSi4 trigonal pyramids that share corners with two equivalent N(1)Si4 trigonal pyramids, corners with two equivalent N(2)Si4 trigonal pyramids, corners with two equivalent O(1)Si4 trigonal pyramids, corners with two equivalent O(2)Si4 trigonal pyramids,  an edgeedge with one N(1)Si4 trigonal pyramid,  an edgeedge with one N(2)Si4 trigonal pyramid,  an edgeedge with one O(1)Si4 trigonal pyramid, and  an edgeedge with one O(2)Si4 trigonal pyramid. In the second N site, N(2) is bonded to one Si(2), one Si(3), and two equivalent Si(1) atoms to form NSi4 trigonal pyramids that share corners with two equivalent N(1)Si4 trigonal pyramids, corners with two equivalent O(2)Si4 trigonal pyramids, corners with four equivalent O(1)Si4 trigonal pyramids,  an edgeedge with one N(1)Si4 trigonal pyramid,  an edgeedge with one N(2)Si4 trigonal pyramid, and  an edgeedge with one O(1)Si4 trigonal pyramid. In the third N site, N(3) is bonded in a see-saw-like geometry to one Si(2), one Si(3), and two equivalent Si(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Si(2), one Si(3), and two equivalent Si(1) atoms to form distorted OSi4 trigonal pyramids that share corners with two equivalent N(1)Si4 trigonal pyramids, corners with two equivalent O(2)Si4 trigonal pyramids, corners with four equivalent N(2)Si4 trigonal pyramids,  an edgeedge with one N(1)Si4 trigonal pyramid,  an edgeedge with one N(2)Si4 trigonal pyramid, and  an edgeedge with one O(1)Si4 trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Si(2) and two equivalent Si(3) atoms to form distorted OSi4 trigonal pyramids that share corners with four equivalent N(1)Si4 trigonal pyramids, corners with four equivalent N(2)Si4 trigonal pyramids, corners with four equivalent O(1)Si4 trigonal pyramids, and edges with two equivalent N(1)Si4 trigonal pyramids. is represented by the CIF card [CIF]
data_Si2N2O
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.708
_cell_length_b   4.708
_cell_length_c   12.796
_cell_angle_alpha   89.917
_cell_angle_beta   89.917
_cell_angle_gamma   59.548
_symmetry_Int_Tables_number   1
_cell_volume   244.484
_cell_formula_units_Z   6
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
  Si  Si0  1  0.315  0.328  0.520  1.0
  Si  Si1  1  0.672  0.685  0.980  1.0
  Si  Si2  1  0.685  0.672  0.480  1.0
  Si  Si3  1  0.328  0.315  0.020  1.0
  Si  Si4  1  0.313  0.332  0.814  1.0
  Si  Si5  1  0.668  0.687  0.686  1.0
  Si  Si6  1  0.687  0.668  0.186  1.0
  Si  Si7  1  0.332  0.313  0.314  1.0
  Si  Si8  1  0.999  0.004  0.853  1.0
  Si  Si9  1  0.996  0.001  0.647  1.0
  Si  Si10  1  0.001  0.996  0.147  1.0
  Si  Si11  1  0.004  0.999  0.353  1.0
  N  N12  1  0.994  0.709  0.752  1.0
  N  N13  1  0.341  0.020  0.417  1.0
  N  N14  1  0.980  0.659  0.083  1.0
  N  N15  1  0.291  0.006  0.748  1.0
  N  N16  1  0.006  0.291  0.248  1.0
  N  N17  1  0.709  0.994  0.252  1.0
  N  N18  1  0.953  0.371  0.585  1.0
  N  N19  1  0.629  0.047  0.915  1.0
  N  N20  1  0.047  0.629  0.415  1.0
  N  N21  1  0.371  0.953  0.085  1.0
  N  N22  1  0.020  0.341  0.917  1.0
  N  N23  1  0.659  0.980  0.583  1.0
  O  O24  1  0.655  0.333  0.418  1.0
  O  O25  1  0.667  0.345  0.082  1.0
  O  O26  1  0.345  0.667  0.582  1.0
  O  O27  1  0.668  0.332  0.750  1.0
  O  O28  1  0.332  0.668  0.250  1.0
  O  O29  1  0.333  0.655  0.918  1.0
[/CIF]
.