Pt5SiSb crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to eight equivalent Pt(2) and four equivalent Si(1) atoms to form PtSi4Pt8 cuboctahedra that share corners with four equivalent Pt(1)Si4Pt8 cuboctahedra, faces with four equivalent Pt(1)Si4Pt8 cuboctahedra, and faces with four equivalent Si(1)Pt12 cuboctahedra. In the second Pt site, Pt(2) is bonded in a 10-coordinate geometry to two equivalent Pt(1), four equivalent Pt(2), two equivalent Si(1), and two equivalent Sb(1) atoms. Si(1) is bonded to four equivalent Pt(1) and eight equivalent Pt(2) atoms to form SiPt12 cuboctahedra that share corners with four equivalent Si(1)Pt12 cuboctahedra, faces with four equivalent Pt(1)Si4Pt8 cuboctahedra, and faces with four equivalent Si(1)Pt12 cuboctahedra. Sb(1) is bonded in a body-centered cubic geometry to eight equivalent Pt(2) atoms.
Pt5SiSb crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to eight equivalent Pt(2) and four equivalent Si(1) atoms to form PtSi4Pt8 cuboctahedra that share corners with four equivalent Pt(1)Si4Pt8 cuboctahedra, faces with four equivalent Pt(1)Si4Pt8 cuboctahedra, and faces with four equivalent Si(1)Pt12 cuboctahedra. All Pt(1)-Pt(2) bond lengths are 2.73 Å. All Pt(1)-Si(1) bond lengths are 2.78 Å. In the second Pt site, Pt(2) is bonded in a 10-coordinate geometry to two equivalent Pt(1), four equivalent Pt(2), two equivalent Si(1), and two equivalent Sb(1) atoms. All Pt(2)-Pt(2) bond lengths are 2.78 Å. Both Pt(2)-Si(1) bond lengths are 2.73 Å. Both Pt(2)-Sb(1) bond lengths are 2.71 Å. Si(1) is bonded to four equivalent Pt(1) and eight equivalent Pt(2) atoms to form SiPt12 cuboctahedra that share corners with four equivalent Si(1)Pt12 cuboctahedra, faces with four equivalent Pt(1)Si4Pt8 cuboctahedra, and faces with four equivalent Si(1)Pt12 cuboctahedra. Sb(1) is bonded in a body-centered cubic geometry to eight equivalent Pt(2) atoms.