Yb3Cu11Si4 crystallizes in the hexagonal P6_3/mmc space group. Yb(1) is bonded in a 15-coordinate geometry to two equivalent Cu(2), two equivalent Cu(3), six equivalent Cu(1), one Si(2), and four equivalent Si(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 12-coordinate geometry to three equivalent Yb(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), one Si(2), and two equivalent Si(1) atoms. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to two equivalent Yb(1), two equivalent Cu(2), two equivalent Cu(3), four equivalent Cu(1), and two equivalent Si(1) atoms. In the third Cu site, Cu(3) is bonded in a 12-coordinate geometry to three equivalent Yb(1), three equivalent Cu(1), three equivalent Cu(2), and three equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Yb(1) and six equivalent Cu(1) atoms. In the second Si site, Si(1) is bonded to four equivalent Yb(1), two equivalent Cu(2), two equivalent Cu(3), and four equivalent Cu(1) atoms to form a mixture of corner and face-sharing SiYb4Cu8 cuboctahedra.
Yb3Cu11Si4 crystallizes in the hexagonal P6_3/mmc space group. Yb(1) is bonded in a 15-coordinate geometry to two equivalent Cu(2), two equivalent Cu(3), six equivalent Cu(1), one Si(2), and four equivalent Si(1) atoms. Both Yb(1)-Cu(2) bond lengths are 2.89 Å. Both Yb(1)-Cu(3) bond lengths are 2.97 Å. There are four shorter (2.92 Å) and two longer (3.02 Å) Yb(1)-Cu(1) bond lengths. The Yb(1)-Si(2) bond length is 2.85 Å. All Yb(1)-Si(1) bond lengths are 3.09 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 12-coordinate geometry to three equivalent Yb(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), one Si(2), and two equivalent Si(1) atoms. The Cu(1)-Cu(3) bond length is 2.74 Å. Both Cu(1)-Cu(2) bond lengths are 2.68 Å. There are two shorter (2.67 Å) and one longer (2.75 Å) Cu(1)-Cu(1) bond length. The Cu(1)-Si(2) bond length is 2.56 Å. Both Cu(1)-Si(1) bond lengths are 2.65 Å. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to two equivalent Yb(1), two equivalent Cu(2), two equivalent Cu(3), four equivalent Cu(1), and two equivalent Si(1) atoms. Both Cu(2)-Cu(2) bond lengths are 2.57 Å. Both Cu(2)-Cu(3) bond lengths are 2.55 Å. Both Cu(2)-Si(1) bond lengths are 2.35 Å. In the third Cu site, Cu(3) is bonded in a 12-coordinate geometry to three equivalent Yb(1), three equivalent Cu(1), three equivalent Cu(2), and three equivalent Si(1) atoms. All Cu(3)-Si(1) bond lengths are 2.40 Å. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Yb(1) and six equivalent Cu(1) atoms. In the second Si site, Si(1) is bonded to four equivalent Yb(1), two equivalent Cu(2), two equivalent Cu(3), and four equivalent Cu(1) atoms to form a mixture of corner and face-sharing SiYb4Cu8 cuboctahedra.