Zr3Cu4Si4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Si(2), and four equivalent Si(1) atoms. In the second Zr site, Zr(2) is bonded to two equivalent Si(2) and four equivalent Si(1) atoms to form distorted edge-sharing ZrSi6 octahedra. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Zr(1), one Cu(1), one Si(1), and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Zr(2), four equivalent Zr(1), two equivalent Cu(1), and one Si(1) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Zr(2), two equivalent Zr(1), and six equivalent Cu(1) atoms.
Zr3Cu4Si4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a 12-coordinate geometry to six equivalent Cu(1), two equivalent Si(2), and four equivalent Si(1) atoms. There are four shorter (2.83 Å) and two longer (2.95 Å) Zr(1)-Cu(1) bond lengths. Both Zr(1)-Si(2) bond lengths are 2.86 Å. All Zr(1)-Si(1) bond lengths are 2.83 Å. In the second Zr site, Zr(2) is bonded to two equivalent Si(2) and four equivalent Si(1) atoms to form distorted edge-sharing ZrSi6 octahedra. Both Zr(2)-Si(2) bond lengths are 2.81 Å. All Zr(2)-Si(1) bond lengths are 2.78 Å. Cu(1) is bonded in a 8-coordinate geometry to three equivalent Zr(1), one Cu(1), one Si(1), and three equivalent Si(2) atoms. The Cu(1)-Cu(1) bond length is 2.44 Å. The Cu(1)-Si(1) bond length is 2.34 Å. There are two shorter (2.39 Å) and one longer (2.47 Å) Cu(1)-Si(2) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Zr(2), four equivalent Zr(1), two equivalent Cu(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.43 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Zr(2), two equivalent Zr(1), and six equivalent Cu(1) atoms.