Pt3Nb is beta Cu3Ti-like structured and crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one Pt(1), two equivalent Pt(4), three equivalent Pt(2), and six equivalent Pt(3) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(2)Pt12 cuboctahedra, corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. In the second Nb site, Nb(2) is bonded to one Pt(2), two equivalent Pt(3), three equivalent Pt(1), and six equivalent Pt(4) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(1)Pt12 cuboctahedra, corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(2)Pt12 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with four equivalent Pt(1)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. There are four inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Nb(1), three equivalent Nb(2), two equivalent Pt(3), and six equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with four equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. In the second Pt site, Pt(2) is bonded in a distorted see-saw-like geometry to one Nb(2), three equivalent Nb(1), two equivalent Pt(4), and six equivalent Pt(3) atoms. In the third Pt site, Pt(3) is bonded to one Nb(2), three equivalent Nb(1), one Pt(1), one Pt(4), three equivalent Pt(2), and three equivalent Pt(3) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with five equivalent Pt(4)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with three equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with three equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Pt(3)Nb4Pt8 cuboctahedra,  a faceface with one Nb(2)Pt12 cuboctahedra,  a faceface with one Pt(1)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with five equivalent Pt(4)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. In the fourth Pt site, Pt(4) is bonded to one Nb(1), three equivalent Nb(2), one Pt(2), one Pt(3), three equivalent Pt(1), and three equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with five equivalent Pt(3)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with three equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(4)Nb4Pt8 cuboctahedra,  a faceface with one Nb(1)Pt12 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, faces with three equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with five equivalent Pt(3)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra.
Pt3Nb is beta Cu3Ti-like structured and crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one Pt(1), two equivalent Pt(4), three equivalent Pt(2), and six equivalent Pt(3) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(2)Pt12 cuboctahedra, corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. The Nb(1)-Pt(1) bond length is 2.80 Å. Both Nb(1)-Pt(4) bond lengths are 2.86 Å. There is one shorter (2.75 Å) and two longer (2.79 Å) Nb(1)-Pt(2) bond lengths. There are two shorter (2.81 Å) and four longer (2.82 Å) Nb(1)-Pt(3) bond lengths. In the second Nb site, Nb(2) is bonded to one Pt(2), two equivalent Pt(3), three equivalent Pt(1), and six equivalent Pt(4) atoms to form NbPt12 cuboctahedra that share  a cornercorner with one Nb(1)Pt12 cuboctahedra, corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(2)Pt12 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with four equivalent Pt(1)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. The Nb(2)-Pt(2) bond length is 2.74 Å. Both Nb(2)-Pt(3) bond lengths are 2.81 Å. There are two shorter (2.79 Å) and one longer (2.86 Å) Nb(2)-Pt(1) bond length. There are four shorter (2.81 Å) and two longer (2.84 Å) Nb(2)-Pt(4) bond lengths. There are four inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Nb(1), three equivalent Nb(2), two equivalent Pt(3), and six equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with four equivalent Nb(1)Pt12 cuboctahedra, corners with four equivalent Nb(2)Pt12 cuboctahedra, corners with four equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with eight equivalent Pt(4)Nb4Pt8 cuboctahedra, faces with two equivalent Nb(1)Pt12 cuboctahedra, faces with two equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with two equivalent Pt(3)Nb4Pt8 cuboctahedra, faces with four equivalent Nb(2)Pt12 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. Both Pt(1)-Pt(3) bond lengths are 2.80 Å. There are two shorter (2.81 Å) and four longer (2.83 Å) Pt(1)-Pt(4) bond lengths. In the second Pt site, Pt(2) is bonded in a distorted see-saw-like geometry to one Nb(2), three equivalent Nb(1), two equivalent Pt(4), and six equivalent Pt(3) atoms. Both Pt(2)-Pt(4) bond lengths are 2.87 Å. There are a spread of Pt(2)-Pt(3) bond distances ranging from 2.78-2.87 Å. In the third Pt site, Pt(3) is bonded to one Nb(2), three equivalent Nb(1), one Pt(1), one Pt(4), three equivalent Pt(2), and three equivalent Pt(3) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(2)Pt12 cuboctahedra, corners with two equivalent Pt(1)Nb4Pt8 cuboctahedra, corners with five equivalent Pt(4)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(2)Pt12 cuboctahedra, edges with three equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with three equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(1)Pt12 cuboctahedra, edges with four equivalent Pt(3)Nb4Pt8 cuboctahedra,  a faceface with one Nb(2)Pt12 cuboctahedra,  a faceface with one Pt(1)Nb4Pt8 cuboctahedra, faces with three equivalent Nb(1)Pt12 cuboctahedra, faces with five equivalent Pt(4)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(3)Nb4Pt8 cuboctahedra. The Pt(3)-Pt(4) bond length is 2.80 Å. There are a spread of Pt(3)-Pt(3) bond distances ranging from 2.78-2.82 Å. In the fourth Pt site, Pt(4) is bonded to one Nb(1), three equivalent Nb(2), one Pt(2), one Pt(3), three equivalent Pt(1), and three equivalent Pt(4) atoms to form distorted PtNb4Pt8 cuboctahedra that share corners with two equivalent Nb(1)Pt12 cuboctahedra, corners with five equivalent Pt(3)Nb4Pt8 cuboctahedra, corners with six equivalent Pt(4)Nb4Pt8 cuboctahedra, edges with three equivalent Nb(1)Pt12 cuboctahedra, edges with three equivalent Pt(3)Nb4Pt8 cuboctahedra, edges with four equivalent Nb(2)Pt12 cuboctahedra, edges with four equivalent Pt(1)Nb4Pt8 cuboctahedra, edges with four equivalent Pt(4)Nb4Pt8 cuboctahedra,  a faceface with one Nb(1)Pt12 cuboctahedra, faces with three equivalent Nb(2)Pt12 cuboctahedra, faces with three equivalent Pt(1)Nb4Pt8 cuboctahedra, faces with five equivalent Pt(3)Nb4Pt8 cuboctahedra, and faces with six equivalent Pt(4)Nb4Pt8 cuboctahedra. There are a spread of Pt(4)-Pt(4) bond distances ranging from 2.77-2.81 Å.