Nd5Ce5Si6 crystallizes in the monoclinic Cm space group. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a distorted trigonal bipyramidal geometry to one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms. In the second Nd site, Nd(2) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(3), and two equivalent Si(4) atoms. In the third Nd site, Nd(3) is bonded in a 5-coordinate geometry to one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms. In the fourth Nd site, Nd(4) is bonded in a 5-coordinate geometry to one Si(2), two equivalent Si(1), and two equivalent Si(4) atoms. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms. In the second Ce site, Ce(2) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(3), and two equivalent Si(4) atoms. In the third Ce site, Ce(3) is bonded in a 5-coordinate geometry to one Si(2), two equivalent Si(1), and two equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Nd(1), one Nd(2), one Nd(3), one Nd(4), one Ce(2), one Ce(3), two equivalent Ce(1), and one Si(1) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Nd(4), two equivalent Nd(2), one Ce(3), two equivalent Ce(1), two equivalent Ce(2), and one Si(3) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Nd(1), one Nd(3), two equivalent Nd(2), two equivalent Ce(1), two equivalent Ce(2), and one Si(2) atom. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to one Nd(1), one Nd(3), one Nd(4), two equivalent Nd(2), one Ce(3), two equivalent Ce(1), and two equivalent Ce(2) atoms.
Nd5Ce5Si6 crystallizes in the monoclinic Cm space group. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a distorted trigonal bipyramidal geometry to one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms. The Nd(1)-Si(3) bond length is 3.06 Å. Both Nd(1)-Si(1) bond lengths are 3.05 Å. Both Nd(1)-Si(4) bond lengths are 3.19 Å. In the second Nd site, Nd(2) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(3), and two equivalent Si(4) atoms. The Nd(2)-Si(1) bond length is 3.01 Å. The Nd(2)-Si(2) bond length is 3.09 Å. The Nd(2)-Si(3) bond length is 3.09 Å. Both Nd(2)-Si(4) bond lengths are 3.19 Å. In the third Nd site, Nd(3) is bonded in a 5-coordinate geometry to one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms. The Nd(3)-Si(3) bond length is 3.02 Å. Both Nd(3)-Si(1) bond lengths are 3.08 Å. Both Nd(3)-Si(4) bond lengths are 3.18 Å. In the fourth Nd site, Nd(4) is bonded in a 5-coordinate geometry to one Si(2), two equivalent Si(1), and two equivalent Si(4) atoms. The Nd(4)-Si(2) bond length is 3.03 Å. Both Nd(4)-Si(1) bond lengths are 3.06 Å. Both Nd(4)-Si(4) bond lengths are 3.23 Å. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), two equivalent Si(1), and two equivalent Si(4) atoms. The Ce(1)-Si(2) bond length is 3.10 Å. The Ce(1)-Si(3) bond length is 3.14 Å. There is one shorter (3.09 Å) and one longer (3.14 Å) Ce(1)-Si(1) bond length. There is one shorter (3.21 Å) and one longer (3.69 Å) Ce(1)-Si(4) bond length. In the second Ce site, Ce(2) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(3), and two equivalent Si(4) atoms. The Ce(2)-Si(1) bond length is 3.01 Å. The Ce(2)-Si(2) bond length is 3.05 Å. The Ce(2)-Si(3) bond length is 3.07 Å. There is one shorter (3.17 Å) and one longer (3.19 Å) Ce(2)-Si(4) bond length. In the third Ce site, Ce(3) is bonded in a 5-coordinate geometry to one Si(2), two equivalent Si(1), and two equivalent Si(4) atoms. The Ce(3)-Si(2) bond length is 3.01 Å. Both Ce(3)-Si(1) bond lengths are 3.07 Å. Both Ce(3)-Si(4) bond lengths are 3.17 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Nd(1), one Nd(2), one Nd(3), one Nd(4), one Ce(2), one Ce(3), two equivalent Ce(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.51 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Nd(4), two equivalent Nd(2), one Ce(3), two equivalent Ce(1), two equivalent Ce(2), and one Si(3) atom. The Si(2)-Si(3) bond length is 2.49 Å. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Nd(1), one Nd(3), two equivalent Nd(2), two equivalent Ce(1), two equivalent Ce(2), and one Si(2) atom. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to one Nd(1), one Nd(3), one Nd(4), two equivalent Nd(2), one Ce(3), two equivalent Ce(1), and two equivalent Ce(2) atoms.