SrYbSi4N7 crystallizes in the hexagonal P6_3mc space group. Sr(1) is bonded to six equivalent N(2) and six equivalent N(3) atoms to form distorted SrN12 cuboctahedra that share corners with twelve equivalent Sr(1)N12 cuboctahedra, edges with three equivalent Si(1)N4 tetrahedra, edges with nine equivalent Si(2)N4 tetrahedra, and faces with four equivalent Yb(1)N6 octahedra. Yb(1) is bonded to three equivalent N(2) and three equivalent N(3) atoms to form YbN6 octahedra that share corners with three equivalent Si(1)N4 tetrahedra, corners with nine equivalent Si(2)N4 tetrahedra, and faces with four equivalent Sr(1)N12 cuboctahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(1) and three equivalent N(3) atoms to form SiN4 tetrahedra that share corners with three equivalent Yb(1)N6 octahedra, corners with six equivalent Si(2)N4 tetrahedra, and edges with three equivalent Sr(1)N12 cuboctahedra. The corner-sharing octahedral tilt angles are 57°. In the second Si site, Si(2) 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 Yb(1)N6 octahedra, corners with two equivalent Si(1)N4 tetrahedra, corners with four equivalent Si(2)N4 tetrahedra, and edges with three equivalent Sr(1)N12 cuboctahedra. The corner-sharing octahedral tilt angles range from 58-63°. There are three inequivalent N sites. In the first N site, N(1) is bonded in a tetrahedral geometry to one Si(1) and three equivalent Si(2) atoms. In the second N site, N(2) is bonded in a 3-coordinate geometry to two equivalent Sr(1), one Yb(1), and two equivalent Si(2) atoms. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1), one Yb(1), one Si(1), and one Si(2) atom.
SrYbSi4N7 crystallizes in the hexagonal P6_3mc space group. Sr(1) is bonded to six equivalent N(2) and six equivalent N(3) atoms to form distorted SrN12 cuboctahedra that share corners with twelve equivalent Sr(1)N12 cuboctahedra, edges with three equivalent Si(1)N4 tetrahedra, edges with nine equivalent Si(2)N4 tetrahedra, and faces with four equivalent Yb(1)N6 octahedra. There are three shorter (2.92 Å) and three longer (3.16 Å) Sr(1)-N(2) bond lengths. All Sr(1)-N(3) bond lengths are 3.05 Å. Yb(1) is bonded to three equivalent N(2) and three equivalent N(3) atoms to form YbN6 octahedra that share corners with three equivalent Si(1)N4 tetrahedra, corners with nine equivalent Si(2)N4 tetrahedra, and faces with four equivalent Sr(1)N12 cuboctahedra. All Yb(1)-N(2) bond lengths are 2.33 Å. All Yb(1)-N(3) bond lengths are 2.37 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(1) and three equivalent N(3) atoms to form SiN4 tetrahedra that share corners with three equivalent Yb(1)N6 octahedra, corners with six equivalent Si(2)N4 tetrahedra, and edges with three equivalent Sr(1)N12 cuboctahedra. The corner-sharing octahedral tilt angles are 57°. The Si(1)-N(1) bond length is 1.86 Å. All Si(1)-N(3) bond lengths are 1.70 Å. In the second Si site, Si(2) 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 Yb(1)N6 octahedra, corners with two equivalent Si(1)N4 tetrahedra, corners with four equivalent Si(2)N4 tetrahedra, and edges with three equivalent Sr(1)N12 cuboctahedra. The corner-sharing octahedral tilt angles range from 58-63°. The Si(2)-N(1) bond length is 1.99 Å. The Si(2)-N(3) bond length is 1.72 Å. Both Si(2)-N(2) bond lengths are 1.72 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded in a tetrahedral geometry to one Si(1) and three equivalent Si(2) atoms. In the second N site, N(2) is bonded in a 3-coordinate geometry to two equivalent Sr(1), one Yb(1), and two equivalent Si(2) atoms. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1), one Yb(1), one Si(1), and one Si(2) atom.