YbEuSi4N7 crystallizes in the hexagonal P6_3mc space group. Yb(1) is bonded to three equivalent N(1) and three equivalent N(2) atoms to form YbN6 octahedra that share corners with three equivalent Si(2)N4 tetrahedra and corners with nine equivalent Si(1)N4 tetrahedra. Eu(1) is bonded in a 12-coordinate geometry to six equivalent N(1) and six equivalent N(2) atoms. There are two inequivalent Si sites. In the first Si site, 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 Yb(1)N6 octahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with four equivalent Si(1)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-62°. In the second Si site, Si(2) is bonded to one N(3) and three equivalent N(1) atoms to form SiN4 tetrahedra that share corners with three equivalent Yb(1)N6 octahedra and corners with six equivalent Si(1)N4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are three inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Yb(1), two equivalent Eu(1), one Si(1), and one Si(2) atom. In the second N site, N(2) is bonded in a 3-coordinate geometry to one Yb(1), two equivalent Eu(1), and two equivalent Si(1) atoms. In the third N site, N(3) is bonded in a tetrahedral geometry to one Si(2) and three equivalent Si(1) atoms.
YbEuSi4N7 crystallizes in the hexagonal P6_3mc space group. Yb(1) is bonded to three equivalent N(1) and three equivalent N(2) atoms to form YbN6 octahedra that share corners with three equivalent Si(2)N4 tetrahedra and corners with nine equivalent Si(1)N4 tetrahedra. All Yb(1)-N(1) bond lengths are 2.34 Å. All Yb(1)-N(2) bond lengths are 2.33 Å. Eu(1) is bonded in a 12-coordinate geometry to six equivalent N(1) and six equivalent N(2) atoms. All Eu(1)-N(1) bond lengths are 3.02 Å. There are three shorter (2.79 Å) and three longer (3.29 Å) Eu(1)-N(2) bond lengths. There are two inequivalent Si sites. In the first Si site, 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 Yb(1)N6 octahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with four equivalent Si(1)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-62°. The Si(1)-N(1) bond length is 1.72 Å. The Si(1)-N(3) bond length is 1.97 Å. Both Si(1)-N(2) bond lengths are 1.72 Å. In the second Si site, Si(2) is bonded to one N(3) and three equivalent N(1) atoms to form SiN4 tetrahedra that share corners with three equivalent Yb(1)N6 octahedra and corners with six equivalent Si(1)N4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. The Si(2)-N(3) bond length is 1.87 Å. All Si(2)-N(1) bond lengths are 1.70 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Yb(1), two equivalent Eu(1), one Si(1), and one Si(2) atom. In the second N site, N(2) is bonded in a 3-coordinate geometry to one Yb(1), two equivalent Eu(1), and two equivalent Si(1) atoms. In the third N site, N(3) is bonded in a tetrahedral geometry to one Si(2) and three equivalent Si(1) atoms.