Nb5PbSe8 crystallizes in the monoclinic C2/m space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of distorted corner and edge-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles are 49°. In the second Nb site, Nb(2) is bonded to one Se(1), two equivalent Se(2), and three equivalent Se(4) atoms to form a mixture of distorted face, corner, and edge-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. In the third Nb site, Nb(3) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form a mixture of distorted face, corner, and edge-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. Pb(1) is bonded in a 12-coordinate geometry to two equivalent Pb(1), two equivalent Se(1), four equivalent Se(2), and four equivalent Se(3) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(3), two equivalent Nb(1), and one Pb(1) atom. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to one Nb(1), two equivalent Nb(2), and two equivalent Pb(1) atoms. In the third Se site, Se(3) is bonded in a 3-coordinate geometry to three equivalent Nb(3) and two equivalent Pb(1) atoms. In the fourth Se site, Se(4) is bonded in a 5-coordinate geometry to two equivalent Nb(3) and three equivalent Nb(2) atoms.
Nb5PbSe8 crystallizes in the monoclinic C2/m space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of distorted corner and edge-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles are 49°. Both Nb(1)-Se(2) bond lengths are 2.66 Å. All Nb(1)-Se(1) bond lengths are 2.67 Å. In the second Nb site, Nb(2) is bonded to one Se(1), two equivalent Se(2), and three equivalent Se(4) atoms to form a mixture of distorted face, corner, and edge-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. The Nb(2)-Se(1) bond length is 2.55 Å. Both Nb(2)-Se(2) bond lengths are 2.55 Å. There are two shorter (2.74 Å) and one longer (2.93 Å) Nb(2)-Se(4) bond length. In the third Nb site, Nb(3) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form a mixture of distorted face, corner, and edge-sharing NbSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. The Nb(3)-Se(1) bond length is 2.73 Å. Both Nb(3)-Se(4) bond lengths are 2.76 Å. There is one shorter (2.57 Å) and two longer (2.61 Å) Nb(3)-Se(3) bond lengths. Pb(1) is bonded in a 12-coordinate geometry to two equivalent Pb(1), two equivalent Se(1), four equivalent Se(2), and four equivalent Se(3) atoms. Both Pb(1)-Pb(1) bond lengths are 3.51 Å. Both Pb(1)-Se(1) bond lengths are 3.38 Å. All Pb(1)-Se(2) bond lengths are 3.44 Å. All Pb(1)-Se(3) bond lengths are 3.27 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Nb(2), one Nb(3), two equivalent Nb(1), and one Pb(1) atom. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to one Nb(1), two equivalent Nb(2), and two equivalent Pb(1) atoms. In the third Se site, Se(3) is bonded in a 3-coordinate geometry to three equivalent Nb(3) and two equivalent Pb(1) atoms. In the fourth Se site, Se(4) is bonded in a 5-coordinate geometry to two equivalent Nb(3) and three equivalent Nb(2) atoms.