CePt5Sb crystallizes in the monoclinic C2/m space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to two equivalent Pt(2), four equivalent Pt(1), and six equivalent Pt(3) atoms to form distorted CePt12 cuboctahedra that share edges with six equivalent Ce(1)Pt12 cuboctahedra, edges with eight equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, edges with six equivalent Ce(2)Sb2Pt18 hexagonal bipyramids, and faces with four equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra. In the second Ce site, Ce(2) is bonded to four equivalent Pt(2), six equivalent Pt(4), eight equivalent Pt(1), and two equivalent Sb(1) atoms to form distorted CeSb2Pt18 hexagonal bipyramids that share edges with six equivalent Ce(1)Pt12 cuboctahedra, faces with sixteen equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, and faces with six equivalent Ce(2)Sb2Pt18 hexagonal bipyramids. There are four inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Ce(1), two equivalent Ce(2), one Pt(3), two equivalent Pt(1), two equivalent Pt(2), two equivalent Pt(4), and two equivalent Sb(1) atoms to form distorted PtCe3Sb2Pt7 cuboctahedra that share corners with ten equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, edges with two equivalent Ce(1)Pt12 cuboctahedra, edges with four equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra,  a faceface with one Ce(1)Pt12 cuboctahedra, faces with five equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, and faces with four equivalent Ce(2)Sb2Pt18 hexagonal bipyramids. In the second Pt site, Pt(2) is bonded in a 12-coordinate geometry to one Ce(1), two equivalent Ce(2), one Pt(3), two equivalent Pt(4), four equivalent Pt(1), and two equivalent Sb(1) atoms. In the third Pt site, Pt(3) is bonded in a 4-coordinate geometry to three equivalent Ce(1), one Pt(2), two equivalent Pt(1), and one Sb(1) atom. In the fourth Pt site, Pt(4) is bonded in a 3-coordinate geometry to three equivalent Ce(2), two equivalent Pt(2), and four equivalent Pt(1) atoms. Sb(1) is bonded in a 8-coordinate geometry to one Ce(2), one Pt(3), two equivalent Pt(2), and four equivalent Pt(1) atoms.
CePt5Sb crystallizes in the monoclinic C2/m space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to two equivalent Pt(2), four equivalent Pt(1), and six equivalent Pt(3) atoms to form distorted CePt12 cuboctahedra that share edges with six equivalent Ce(1)Pt12 cuboctahedra, edges with eight equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, edges with six equivalent Ce(2)Sb2Pt18 hexagonal bipyramids, and faces with four equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra. Both Ce(1)-Pt(2) bond lengths are 3.21 Å. All Ce(1)-Pt(1) bond lengths are 3.30 Å. There are four shorter (3.13 Å) and two longer (3.24 Å) Ce(1)-Pt(3) bond lengths. In the second Ce site, Ce(2) is bonded to four equivalent Pt(2), six equivalent Pt(4), eight equivalent Pt(1), and two equivalent Sb(1) atoms to form distorted CeSb2Pt18 hexagonal bipyramids that share edges with six equivalent Ce(1)Pt12 cuboctahedra, faces with sixteen equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, and faces with six equivalent Ce(2)Sb2Pt18 hexagonal bipyramids. All Ce(2)-Pt(2) bond lengths are 3.63 Å. There are four shorter (3.10 Å) and two longer (3.15 Å) Ce(2)-Pt(4) bond lengths. There are four shorter (3.54 Å) and four longer (3.57 Å) Ce(2)-Pt(1) bond lengths. Both Ce(2)-Sb(1) bond lengths are 3.25 Å. There are four inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Ce(1), two equivalent Ce(2), one Pt(3), two equivalent Pt(1), two equivalent Pt(2), two equivalent Pt(4), and two equivalent Sb(1) atoms to form distorted PtCe3Sb2Pt7 cuboctahedra that share corners with ten equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, edges with two equivalent Ce(1)Pt12 cuboctahedra, edges with four equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra,  a faceface with one Ce(1)Pt12 cuboctahedra, faces with five equivalent Pt(1)Ce3Sb2Pt7 cuboctahedra, and faces with four equivalent Ce(2)Sb2Pt18 hexagonal bipyramids. The Pt(1)-Pt(3) bond length is 2.81 Å. There is one shorter (2.69 Å) and one longer (2.72 Å) Pt(1)-Pt(1) bond length. There is one shorter (2.69 Å) and one longer (2.71 Å) Pt(1)-Pt(2) bond length. There is one shorter (2.78 Å) and one longer (2.84 Å) Pt(1)-Pt(4) bond length. Both Pt(1)-Sb(1) bond lengths are 2.85 Å. In the second Pt site, Pt(2) is bonded in a 12-coordinate geometry to one Ce(1), two equivalent Ce(2), one Pt(3), two equivalent Pt(4), four equivalent Pt(1), and two equivalent Sb(1) atoms. The Pt(2)-Pt(3) bond length is 2.80 Å. There is one shorter (2.80 Å) and one longer (2.90 Å) Pt(2)-Pt(4) bond length. Both Pt(2)-Sb(1) bond lengths are 2.83 Å. In the third Pt site, Pt(3) is bonded in a 4-coordinate geometry to three equivalent Ce(1), one Pt(2), two equivalent Pt(1), and one Sb(1) atom. The Pt(3)-Sb(1) bond length is 2.54 Å. In the fourth Pt site, Pt(4) is bonded in a 3-coordinate geometry to three equivalent Ce(2), two equivalent Pt(2), and four equivalent Pt(1) atoms. Sb(1) is bonded in a 8-coordinate geometry to one Ce(2), one Pt(3), two equivalent Pt(2), and four equivalent Pt(1) atoms.