EuNiSi3 crystallizes in the tetragonal I4mm space group. Eu(1) is bonded in a 17-coordinate geometry to five equivalent Ni(1), four equivalent Si(2), and eight equivalent Si(1) atoms. Ni(1) is bonded in a 5-coordinate geometry to five equivalent Eu(1), one Si(2), and four equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to four equivalent Eu(1), two equivalent Ni(1), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Eu(1), one Ni(1), and four equivalent Si(1) atoms.
EuNiSi3 crystallizes in the tetragonal I4mm space group. Eu(1) is bonded in a 17-coordinate geometry to five equivalent Ni(1), four equivalent Si(2), and eight equivalent Si(1) atoms. There are four shorter (3.26 Å) and one longer (3.35 Å) Eu(1)-Ni(1) bond length. All Eu(1)-Si(2) bond lengths are 3.04 Å. There are four shorter (3.12 Å) and four longer (3.20 Å) Eu(1)-Si(1) bond lengths. Ni(1) is bonded in a 5-coordinate geometry to five equivalent Eu(1), one Si(2), and four equivalent Si(1) atoms. The Ni(1)-Si(2) bond length is 2.29 Å. All Ni(1)-Si(1) bond lengths are 2.30 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to four equivalent Eu(1), two equivalent Ni(1), and two equivalent Si(2) atoms. Both Si(1)-Si(2) bond lengths are 2.55 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Eu(1), one Ni(1), and four equivalent Si(1) atoms.