U2Ni2Si7 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to two equivalent Si(1), two equivalent Si(4), two equivalent Si(6), four equivalent Si(5), and four equivalent Si(7) atoms. In the second U site, U(2) is bonded in a 14-coordinate geometry to four equivalent Ni(2), two equivalent Si(2), two equivalent Si(3), two equivalent Si(5), and four equivalent Si(6) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a body-centered cubic geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(2), one Si(6), two equivalent Si(2), and two equivalent Si(3) atoms. There are seven inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(2), and two equivalent Si(7) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(3), and two equivalent Si(7) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), one Si(7), and two equivalent Si(6) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Ni(2), and two equivalent Si(5) atoms. In the seventh Si site, Si(7) is bonded in a 9-coordinate geometry to four equivalent U(1), one Si(5), two equivalent Si(1), and two equivalent Si(4) atoms.
U2Ni2Si7 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to two equivalent Si(1), two equivalent Si(4), two equivalent Si(6), four equivalent Si(5), and four equivalent Si(7) atoms. Both U(1)-Si(1) bond lengths are 3.05 Å. Both U(1)-Si(4) bond lengths are 3.10 Å. Both U(1)-Si(6) bond lengths are 3.16 Å. All U(1)-Si(5) bond lengths are 3.12 Å. All U(1)-Si(7) bond lengths are 2.99 Å. In the second U site, U(2) is bonded in a 14-coordinate geometry to four equivalent Ni(2), two equivalent Si(2), two equivalent Si(3), two equivalent Si(5), and four equivalent Si(6) atoms. All U(2)-Ni(2) bond lengths are 3.09 Å. Both U(2)-Si(2) bond lengths are 3.06 Å. Both U(2)-Si(3) bond lengths are 3.08 Å. Both U(2)-Si(5) bond lengths are 2.94 Å. All U(2)-Si(6) bond lengths are 3.01 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a body-centered cubic geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. Both Ni(1)-Si(1) bond lengths are 2.30 Å. Both Ni(1)-Si(2) bond lengths are 2.42 Å. Both Ni(1)-Si(3) bond lengths are 2.45 Å. Both Ni(1)-Si(4) bond lengths are 2.31 Å. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(2), one Si(6), two equivalent Si(2), and two equivalent Si(3) atoms. The Ni(2)-Si(6) bond length is 2.25 Å. Both Ni(2)-Si(2) bond lengths are 2.30 Å. Both Ni(2)-Si(3) bond lengths are 2.27 Å. There are seven inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(2), and two equivalent Si(7) atoms. The Si(1)-Si(2) bond length is 2.54 Å. Both Si(1)-Si(7) bond lengths are 2.43 Å. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(1) atom. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to two equivalent U(2), two equivalent Ni(1), two equivalent Ni(2), and one Si(4) atom. The Si(3)-Si(4) bond length is 2.51 Å. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to two equivalent U(1), two equivalent Ni(1), one Si(3), and two equivalent Si(7) atoms. Both Si(4)-Si(7) bond lengths are 2.42 Å. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent U(2), four equivalent U(1), one Si(7), and two equivalent Si(6) atoms. The Si(5)-Si(7) bond length is 2.27 Å. Both Si(5)-Si(6) bond lengths are 2.33 Å. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent U(1), four equivalent U(2), one Ni(2), and two equivalent Si(5) atoms. In the seventh Si site, Si(7) is bonded in a 9-coordinate geometry to four equivalent U(1), one Si(5), two equivalent Si(1), and two equivalent Si(4) atoms.