The material described by Y2Si4N6C crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one N(2), one N(3), one N(4), one N(6), and two equivalent N(1) atoms to form distorted YN6 pentagonal pyramids that share corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, corners with three equivalent Si(2)CN3 tetrahedra, corners with three equivalent Si(4)CN3 tetrahedra,  an edgeedge with one Y(1)N6 pentagonal pyramid, and  an edgeedge with one Si(1)CN3 tetrahedra. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one N(2), one N(3), one N(4), one N(6), and two equivalent N(5) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one C(1), one N(1), one N(2), and one N(3) atom to form SiCN3 tetrahedra that share corners with two equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(2)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, corners with two equivalent Si(4)CN3 tetrahedra, and  an edgeedge with one Y(1)N6 pentagonal pyramid. In the second Si site, Si(2) is bonded to one C(1), one N(2), one N(4), and one N(6) atom to form SiCN3 tetrahedra that share corners with three equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, and corners with two equivalent Si(4)CN3 tetrahedra. In the third Si site, Si(3) is bonded to one C(1), one N(3), one N(5), and one N(6) atom to form SiCN3 tetrahedra that share corners with two equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, and corners with two equivalent Si(4)CN3 tetrahedra. In the fourth Si site, Si(4) is bonded to one C(1), one N(1), one N(4), and one N(5) atom to form SiCN3 tetrahedra that share corners with three equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, and corners with two equivalent Si(3)CN3 tetrahedra. C(1) is bonded to one Si(1), one Si(2), one Si(3), and one Si(4) atom to form CSi4 tetrahedra that share corners with two equivalent N(1)Y2Si2 tetrahedra, corners with two equivalent N(4)Y2Si2 tetrahedra, corners with two equivalent N(5)Y2Si2 tetrahedra, and corners with two equivalent N(2)Y2Si2 trigonal pyramids. There are six inequivalent N sites. In the first N site, N(2) is bonded to one Y(1), one Y(2), one Si(1), and one Si(2) atom to form distorted NY2Si2 trigonal pyramids that share  a cornercorner with one N(4)Y2Si2 tetrahedra, corners with two equivalent C(1)Si4 tetrahedra, corners with two equivalent N(5)Y2Si2 tetrahedra, corners with three equivalent N(1)Y2Si2 tetrahedra, and  an edgeedge with one N(4)Y2Si2 tetrahedra. In the second N site, N(3) is bonded in a 4-coordinate geometry to one Y(1), one Y(2), one Si(1), and one Si(3) atom. In the third N site, N(4) is bonded to one Y(1), one Y(2), one Si(2), and one Si(4) atom to form distorted NY2Si2 tetrahedra that share corners with two equivalent C(1)Si4 tetrahedra, corners with three equivalent N(1)Y2Si2 tetrahedra, corners with three equivalent N(5)Y2Si2 tetrahedra,  a cornercorner with one N(2)Y2Si2 trigonal pyramid, and  an edgeedge with one N(2)Y2Si2 trigonal pyramid. In the fourth N site, N(5) is bonded to two equivalent Y(2), one Si(3), and one Si(4) atom to form distorted NY2Si2 tetrahedra that share  a cornercorner with one N(1)Y2Si2 tetrahedra, corners with two equivalent C(1)Si4 tetrahedra, corners with three equivalent N(4)Y2Si2 tetrahedra, corners with two equivalent N(2)Y2Si2 trigonal pyramids, and  an edgeedge with one N(5)Y2Si2 tetrahedra. In the fifth N site, N(6) is bonded in a 3-coordinate geometry to one Y(1), one Y(2), one Si(2), and one Si(3) atom. In the sixth N site, N(1) is bonded to two equivalent Y(1), one Si(1), and one Si(4) atom to form distorted NY2Si2 tetrahedra that share  a cornercorner with one N(5)Y2Si2 tetrahedra, corners with two equivalent C(1)Si4 tetrahedra, corners with three equivalent N(4)Y2Si2 tetrahedra, corners with three equivalent N(2)Y2Si2 trigonal pyramids, and  an edgeedge with one N(1)Y2Si2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2Si4CN6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.923
_cell_length_b   5.923
_cell_length_c   11.881
_cell_angle_alpha   60.375
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   607.076
_cell_formula_units_Z   4
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
  Y  Y0  1  0.413  0.344  0.418  1.0
  Y  Y1  1  0.913  0.656  0.082  1.0
  Y  Y2  1  0.587  0.656  0.582  1.0
  Y  Y3  1  0.087  0.344  0.918  1.0
  Y  Y4  1  0.567  0.671  0.094  1.0
  Y  Y5  1  0.067  0.329  0.406  1.0
  Y  Y6  1  0.433  0.329  0.906  1.0
  Y  Y7  1  0.933  0.671  0.594  1.0
  Si  Si8  1  0.227  0.323  0.159  1.0
  Si  Si9  1  0.727  0.677  0.341  1.0
  Si  Si10  1  0.773  0.677  0.841  1.0
  Si  Si11  1  0.273  0.323  0.659  1.0
  Si  Si12  1  0.206  0.799  0.176  1.0
  Si  Si13  1  0.706  0.201  0.324  1.0
  Si  Si14  1  0.794  0.201  0.824  1.0
  Si  Si15  1  0.294  0.799  0.676  1.0
  Si  Si16  1  0.212  0.836  0.421  1.0
  Si  Si17  1  0.712  0.164  0.079  1.0
  Si  Si18  1  0.788  0.164  0.579  1.0
  Si  Si19  1  0.288  0.836  0.921  1.0
  Si  Si20  1  0.480  0.996  0.250  1.0
  Si  Si21  1  0.980  0.004  0.250  1.0
  Si  Si22  1  0.520  0.004  0.750  1.0
  Si  Si23  1  0.020  0.996  0.750  1.0
  C  C24  1  0.292  0.976  0.253  1.0
  C  C25  1  0.792  0.024  0.247  1.0
  C  C26  1  0.708  0.024  0.747  1.0
  C  C27  1  0.208  0.976  0.753  1.0
  N  N28  1  0.054  0.298  0.137  1.0
  N  N29  1  0.554  0.702  0.363  1.0
  N  N30  1  0.946  0.702  0.863  1.0
  N  N31  1  0.446  0.298  0.637  1.0
  N  N32  1  0.262  0.482  0.245  1.0
  N  N33  1  0.762  0.518  0.255  1.0
  N  N34  1  0.738  0.518  0.755  1.0
  N  N35  1  0.238  0.482  0.745  1.0
  N  N36  1  0.289  0.496  0.001  1.0
  N  N37  1  0.789  0.504  0.499  1.0
  N  N38  1  0.711  0.504  0.999  1.0
  N  N39  1  0.211  0.496  0.501  1.0
  N  N40  1  0.036  0.759  0.222  1.0
  N  N41  1  0.536  0.241  0.278  1.0
  N  N42  1  0.964  0.241  0.778  1.0
  N  N43  1  0.464  0.759  0.722  1.0
  N  N44  1  0.044  0.940  0.399  1.0
  N  N45  1  0.544  0.060  0.101  1.0
  N  N46  1  0.956  0.060  0.601  1.0
  N  N47  1  0.456  0.940  0.899  1.0
  N  N48  1  0.285  0.961  0.510  1.0
  N  N49  1  0.785  0.039  0.990  1.0
  N  N50  1  0.715  0.039  0.490  1.0
  N  N51  1  0.215  0.961  0.010  1.0
[/CIF]
.
The material described by Y2Si4N6C crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one N(2), one N(3), one N(4), one N(6), and two equivalent N(1) atoms to form distorted YN6 pentagonal pyramids that share corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, corners with three equivalent Si(2)CN3 tetrahedra, corners with three equivalent Si(4)CN3 tetrahedra,  an edgeedge with one Y(1)N6 pentagonal pyramid, and  an edgeedge with one Si(1)CN3 tetrahedra. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one N(2), one N(3), one N(4), one N(6), and two equivalent N(5) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one C(1), one N(1), one N(2), and one N(3) atom to form SiCN3 tetrahedra that share corners with two equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(2)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, corners with two equivalent Si(4)CN3 tetrahedra, and  an edgeedge with one Y(1)N6 pentagonal pyramid. In the second Si site, Si(2) is bonded to one C(1), one N(2), one N(4), and one N(6) atom to form SiCN3 tetrahedra that share corners with three equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, and corners with two equivalent Si(4)CN3 tetrahedra. In the third Si site, Si(3) is bonded to one C(1), one N(3), one N(5), and one N(6) atom to form SiCN3 tetrahedra that share corners with two equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, and corners with two equivalent Si(4)CN3 tetrahedra. In the fourth Si site, Si(4) is bonded to one C(1), one N(1), one N(4), and one N(5) atom to form SiCN3 tetrahedra that share corners with three equivalent Y(1)N6 pentagonal pyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, and corners with two equivalent Si(3)CN3 tetrahedra. C(1) is bonded to one Si(1), one Si(2), one Si(3), and one Si(4) atom to form CSi4 tetrahedra that share corners with two equivalent N(1)Y2Si2 tetrahedra, corners with two equivalent N(4)Y2Si2 tetrahedra, corners with two equivalent N(5)Y2Si2 tetrahedra, and corners with two equivalent N(2)Y2Si2 trigonal pyramids. There are six inequivalent N sites. In the first N site, N(2) is bonded to one Y(1), one Y(2), one Si(1), and one Si(2) atom to form distorted NY2Si2 trigonal pyramids that share  a cornercorner with one N(4)Y2Si2 tetrahedra, corners with two equivalent C(1)Si4 tetrahedra, corners with two equivalent N(5)Y2Si2 tetrahedra, corners with three equivalent N(1)Y2Si2 tetrahedra, and  an edgeedge with one N(4)Y2Si2 tetrahedra. In the second N site, N(3) is bonded in a 4-coordinate geometry to one Y(1), one Y(2), one Si(1), and one Si(3) atom. In the third N site, N(4) is bonded to one Y(1), one Y(2), one Si(2), and one Si(4) atom to form distorted NY2Si2 tetrahedra that share corners with two equivalent C(1)Si4 tetrahedra, corners with three equivalent N(1)Y2Si2 tetrahedra, corners with three equivalent N(5)Y2Si2 tetrahedra,  a cornercorner with one N(2)Y2Si2 trigonal pyramid, and  an edgeedge with one N(2)Y2Si2 trigonal pyramid. In the fourth N site, N(5) is bonded to two equivalent Y(2), one Si(3), and one Si(4) atom to form distorted NY2Si2 tetrahedra that share  a cornercorner with one N(1)Y2Si2 tetrahedra, corners with two equivalent C(1)Si4 tetrahedra, corners with three equivalent N(4)Y2Si2 tetrahedra, corners with two equivalent N(2)Y2Si2 trigonal pyramids, and  an edgeedge with one N(5)Y2Si2 tetrahedra. In the fifth N site, N(6) is bonded in a 3-coordinate geometry to one Y(1), one Y(2), one Si(2), and one Si(3) atom. In the sixth N site, N(1) is bonded to two equivalent Y(1), one Si(1), and one Si(4) atom to form distorted NY2Si2 tetrahedra that share  a cornercorner with one N(5)Y2Si2 tetrahedra, corners with two equivalent C(1)Si4 tetrahedra, corners with three equivalent N(4)Y2Si2 tetrahedra, corners with three equivalent N(2)Y2Si2 trigonal pyramids, and  an edgeedge with one N(1)Y2Si2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2Si4CN6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.923
_cell_length_b   5.923
_cell_length_c   11.881
_cell_angle_alpha   60.375
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   607.076
_cell_formula_units_Z   4
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
  Y  Y0  1  0.413  0.344  0.418  1.0
  Y  Y1  1  0.913  0.656  0.082  1.0
  Y  Y2  1  0.587  0.656  0.582  1.0
  Y  Y3  1  0.087  0.344  0.918  1.0
  Y  Y4  1  0.567  0.671  0.094  1.0
  Y  Y5  1  0.067  0.329  0.406  1.0
  Y  Y6  1  0.433  0.329  0.906  1.0
  Y  Y7  1  0.933  0.671  0.594  1.0
  Si  Si8  1  0.227  0.323  0.159  1.0
  Si  Si9  1  0.727  0.677  0.341  1.0
  Si  Si10  1  0.773  0.677  0.841  1.0
  Si  Si11  1  0.273  0.323  0.659  1.0
  Si  Si12  1  0.206  0.799  0.176  1.0
  Si  Si13  1  0.706  0.201  0.324  1.0
  Si  Si14  1  0.794  0.201  0.824  1.0
  Si  Si15  1  0.294  0.799  0.676  1.0
  Si  Si16  1  0.212  0.836  0.421  1.0
  Si  Si17  1  0.712  0.164  0.079  1.0
  Si  Si18  1  0.788  0.164  0.579  1.0
  Si  Si19  1  0.288  0.836  0.921  1.0
  Si  Si20  1  0.480  0.996  0.250  1.0
  Si  Si21  1  0.980  0.004  0.250  1.0
  Si  Si22  1  0.520  0.004  0.750  1.0
  Si  Si23  1  0.020  0.996  0.750  1.0
  C  C24  1  0.292  0.976  0.253  1.0
  C  C25  1  0.792  0.024  0.247  1.0
  C  C26  1  0.708  0.024  0.747  1.0
  C  C27  1  0.208  0.976  0.753  1.0
  N  N28  1  0.054  0.298  0.137  1.0
  N  N29  1  0.554  0.702  0.363  1.0
  N  N30  1  0.946  0.702  0.863  1.0
  N  N31  1  0.446  0.298  0.637  1.0
  N  N32  1  0.262  0.482  0.245  1.0
  N  N33  1  0.762  0.518  0.255  1.0
  N  N34  1  0.738  0.518  0.755  1.0
  N  N35  1  0.238  0.482  0.745  1.0
  N  N36  1  0.289  0.496  0.001  1.0
  N  N37  1  0.789  0.504  0.499  1.0
  N  N38  1  0.711  0.504  0.999  1.0
  N  N39  1  0.211  0.496  0.501  1.0
  N  N40  1  0.036  0.759  0.222  1.0
  N  N41  1  0.536  0.241  0.278  1.0
  N  N42  1  0.964  0.241  0.778  1.0
  N  N43  1  0.464  0.759  0.722  1.0
  N  N44  1  0.044  0.940  0.399  1.0
  N  N45  1  0.544  0.060  0.101  1.0
  N  N46  1  0.956  0.060  0.601  1.0
  N  N47  1  0.456  0.940  0.899  1.0
  N  N48  1  0.285  0.961  0.510  1.0
  N  N49  1  0.785  0.039  0.990  1.0
  N  N50  1  0.715  0.039  0.490  1.0
  N  N51  1  0.215  0.961  0.010  1.0
[/CIF]
.