The structure described by La2Si4N6C crystallizes in the orthorhombic Pnma space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 11-coordinate geometry to two equivalent N(3), two equivalent N(4), three equivalent N(1), and four equivalent N(2) atoms. In the second La site, La(2) is bonded to one N(4), two equivalent N(2), and four equivalent N(3) atoms to form distorted LaN7 pentagonal bipyramids that share corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, corners with four equivalent Si(3)CN3 tetrahedra, edges with two equivalent La(2)N7 pentagonal bipyramids,  an edgeedge with one Si(1)CN3 tetrahedra, and edges with two equivalent Si(3)CN3 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one C(1), one N(1), and two equivalent N(3) atoms to form SiCN3 tetrahedra that share corners with two equivalent La(2)N7 pentagonal bipyramids, corners with two equivalent Si(2)CN3 tetrahedra, corners with four equivalent Si(3)CN3 tetrahedra, and  an edgeedge with one La(2)N7 pentagonal bipyramid. In the second Si site, Si(2) is bonded to one C(1), one N(1), and two equivalent N(2) atoms to form SiCN3 tetrahedra that share corners with two equivalent La(2)N7 pentagonal bipyramids, corners with two equivalent Si(1)CN3 tetrahedra, and corners with four equivalent Si(3)CN3 tetrahedra. In the third Si site, Si(3) is bonded to one C(1), one N(2), one N(3), and one N(4) atom to form SiCN3 tetrahedra that share corners with two equivalent La(2)N7 pentagonal bipyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, and  an edgeedge with one La(2)N7 pentagonal bipyramid. C(1) is bonded in a tetrahedral geometry to one Si(1), one Si(2), and two equivalent Si(3) atoms. There are four inequivalent N sites. In the first N site, N(3) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Si(1), and one Si(3) atom. In the second N site, N(4) is bonded in a 5-coordinate geometry to one La(2), two equivalent La(1), and two equivalent Si(3) atoms. In the third N site, N(1) is bonded in a 3-coordinate geometry to three equivalent La(1), one Si(1), and one Si(2) atom. In the fourth N site, N(2) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), one Si(2), and one Si(3) atom. is represented by the CIF card [CIF]
data_La2Si4CN6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.041
_cell_length_b   10.229
_cell_length_c   10.591
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   654.465
_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
  La  La0  1  0.750  0.049  0.396  1.0
  La  La1  1  0.250  0.451  0.896  1.0
  La  La2  1  0.750  0.407  0.439  1.0
  La  La3  1  0.250  0.093  0.939  1.0
  La  La4  1  0.750  0.907  0.061  1.0
  La  La5  1  0.250  0.593  0.561  1.0
  La  La6  1  0.750  0.549  0.104  1.0
  La  La7  1  0.250  0.951  0.604  1.0
  Si  Si8  1  0.750  0.518  0.739  1.0
  Si  Si9  1  0.250  0.982  0.239  1.0
  Si  Si10  1  0.750  0.018  0.761  1.0
  Si  Si11  1  0.250  0.482  0.261  1.0
  Si  Si12  1  0.750  0.298  0.925  1.0
  Si  Si13  1  0.250  0.202  0.425  1.0
  Si  Si14  1  0.750  0.798  0.575  1.0
  Si  Si15  1  0.250  0.702  0.075  1.0
  Si  Si16  1  0.503  0.727  0.330  1.0
  Si  Si17  1  0.497  0.773  0.830  1.0
  Si  Si18  1  0.997  0.227  0.170  1.0
  Si  Si19  1  0.003  0.273  0.670  1.0
  Si  Si20  1  0.497  0.273  0.670  1.0
  Si  Si21  1  0.503  0.227  0.170  1.0
  Si  Si22  1  0.003  0.773  0.830  1.0
  Si  Si23  1  0.997  0.727  0.330  1.0
  C  C24  1  0.750  0.205  0.764  1.0
  C  C25  1  0.250  0.295  0.264  1.0
  C  C26  1  0.750  0.705  0.736  1.0
  C  C27  1  0.250  0.795  0.236  1.0
  N  N28  1  0.750  0.966  0.607  1.0
  N  N29  1  0.250  0.534  0.107  1.0
  N  N30  1  0.009  0.720  0.986  1.0
  N  N31  1  0.991  0.780  0.486  1.0
  N  N32  1  0.491  0.220  0.514  1.0
  N  N33  1  0.509  0.280  0.014  1.0
  N  N34  1  0.991  0.280  0.014  1.0
  N  N35  1  0.009  0.220  0.514  1.0
  N  N36  1  0.509  0.780  0.486  1.0
  N  N37  1  0.980  0.446  0.665  1.0
  N  N38  1  0.520  0.446  0.665  1.0
  N  N39  1  0.480  0.054  0.165  1.0
  N  N40  1  0.980  0.946  0.835  1.0
  N  N41  1  0.020  0.554  0.335  1.0
  N  N42  1  0.250  0.231  0.747  1.0
  N  N43  1  0.750  0.269  0.247  1.0
  N  N44  1  0.250  0.731  0.753  1.0
  N  N45  1  0.750  0.769  0.253  1.0
  N  N46  1  0.491  0.720  0.986  1.0
  N  N47  1  0.480  0.554  0.335  1.0
  N  N48  1  0.520  0.946  0.835  1.0
  N  N49  1  0.020  0.054  0.165  1.0
  N  N50  1  0.750  0.466  0.893  1.0
  N  N51  1  0.250  0.034  0.393  1.0
[/CIF]
.
The structure described by La2Si4N6C crystallizes in the orthorhombic Pnma space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 11-coordinate geometry to two equivalent N(3), two equivalent N(4), three equivalent N(1), and four equivalent N(2) atoms. In the second La site, La(2) is bonded to one N(4), two equivalent N(2), and four equivalent N(3) atoms to form distorted LaN7 pentagonal bipyramids that share corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, corners with four equivalent Si(3)CN3 tetrahedra, edges with two equivalent La(2)N7 pentagonal bipyramids,  an edgeedge with one Si(1)CN3 tetrahedra, and edges with two equivalent Si(3)CN3 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one C(1), one N(1), and two equivalent N(3) atoms to form SiCN3 tetrahedra that share corners with two equivalent La(2)N7 pentagonal bipyramids, corners with two equivalent Si(2)CN3 tetrahedra, corners with four equivalent Si(3)CN3 tetrahedra, and  an edgeedge with one La(2)N7 pentagonal bipyramid. In the second Si site, Si(2) is bonded to one C(1), one N(1), and two equivalent N(2) atoms to form SiCN3 tetrahedra that share corners with two equivalent La(2)N7 pentagonal bipyramids, corners with two equivalent Si(1)CN3 tetrahedra, and corners with four equivalent Si(3)CN3 tetrahedra. In the third Si site, Si(3) is bonded to one C(1), one N(2), one N(3), and one N(4) atom to form SiCN3 tetrahedra that share corners with two equivalent La(2)N7 pentagonal bipyramids, corners with two equivalent Si(1)CN3 tetrahedra, corners with two equivalent Si(2)CN3 tetrahedra, corners with two equivalent Si(3)CN3 tetrahedra, and  an edgeedge with one La(2)N7 pentagonal bipyramid. C(1) is bonded in a tetrahedral geometry to one Si(1), one Si(2), and two equivalent Si(3) atoms. There are four inequivalent N sites. In the first N site, N(3) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Si(1), and one Si(3) atom. In the second N site, N(4) is bonded in a 5-coordinate geometry to one La(2), two equivalent La(1), and two equivalent Si(3) atoms. In the third N site, N(1) is bonded in a 3-coordinate geometry to three equivalent La(1), one Si(1), and one Si(2) atom. In the fourth N site, N(2) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), one Si(2), and one Si(3) atom. is represented by the CIF card [CIF]
data_La2Si4CN6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.041
_cell_length_b   10.229
_cell_length_c   10.591
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   654.465
_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
  La  La0  1  0.750  0.049  0.396  1.0
  La  La1  1  0.250  0.451  0.896  1.0
  La  La2  1  0.750  0.407  0.439  1.0
  La  La3  1  0.250  0.093  0.939  1.0
  La  La4  1  0.750  0.907  0.061  1.0
  La  La5  1  0.250  0.593  0.561  1.0
  La  La6  1  0.750  0.549  0.104  1.0
  La  La7  1  0.250  0.951  0.604  1.0
  Si  Si8  1  0.750  0.518  0.739  1.0
  Si  Si9  1  0.250  0.982  0.239  1.0
  Si  Si10  1  0.750  0.018  0.761  1.0
  Si  Si11  1  0.250  0.482  0.261  1.0
  Si  Si12  1  0.750  0.298  0.925  1.0
  Si  Si13  1  0.250  0.202  0.425  1.0
  Si  Si14  1  0.750  0.798  0.575  1.0
  Si  Si15  1  0.250  0.702  0.075  1.0
  Si  Si16  1  0.503  0.727  0.330  1.0
  Si  Si17  1  0.497  0.773  0.830  1.0
  Si  Si18  1  0.997  0.227  0.170  1.0
  Si  Si19  1  0.003  0.273  0.670  1.0
  Si  Si20  1  0.497  0.273  0.670  1.0
  Si  Si21  1  0.503  0.227  0.170  1.0
  Si  Si22  1  0.003  0.773  0.830  1.0
  Si  Si23  1  0.997  0.727  0.330  1.0
  C  C24  1  0.750  0.205  0.764  1.0
  C  C25  1  0.250  0.295  0.264  1.0
  C  C26  1  0.750  0.705  0.736  1.0
  C  C27  1  0.250  0.795  0.236  1.0
  N  N28  1  0.750  0.966  0.607  1.0
  N  N29  1  0.250  0.534  0.107  1.0
  N  N30  1  0.009  0.720  0.986  1.0
  N  N31  1  0.991  0.780  0.486  1.0
  N  N32  1  0.491  0.220  0.514  1.0
  N  N33  1  0.509  0.280  0.014  1.0
  N  N34  1  0.991  0.280  0.014  1.0
  N  N35  1  0.009  0.220  0.514  1.0
  N  N36  1  0.509  0.780  0.486  1.0
  N  N37  1  0.980  0.446  0.665  1.0
  N  N38  1  0.520  0.446  0.665  1.0
  N  N39  1  0.480  0.054  0.165  1.0
  N  N40  1  0.980  0.946  0.835  1.0
  N  N41  1  0.020  0.554  0.335  1.0
  N  N42  1  0.250  0.231  0.747  1.0
  N  N43  1  0.750  0.269  0.247  1.0
  N  N44  1  0.250  0.731  0.753  1.0
  N  N45  1  0.750  0.769  0.253  1.0
  N  N46  1  0.491  0.720  0.986  1.0
  N  N47  1  0.480  0.554  0.335  1.0
  N  N48  1  0.520  0.946  0.835  1.0
  N  N49  1  0.020  0.054  0.165  1.0
  N  N50  1  0.750  0.466  0.893  1.0
  N  N51  1  0.250  0.034  0.393  1.0
[/CIF]
.