Ni3Bi2Se2 crystallizes in the monoclinic C2/m space group. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a distorted linear geometry to two equivalent Bi(1), two equivalent Bi(2), and two equivalent Se(1) atoms. In the second Ni site, Ni(2) is bonded in a distorted linear geometry to two equivalent Bi(1), two equivalent Bi(2), and two equivalent Se(1) atoms. In the third Ni site, Ni(3) is bonded in a distorted linear geometry to two equivalent Bi(1), two equivalent Bi(2), and two equivalent Se(1) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 6-coordinate geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent Ni(3) atoms. In the second Bi site, Bi(2) is bonded in a 6-coordinate geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent Ni(3) atoms. Se(1) is bonded in a distorted T-shaped geometry to one Ni(1), one Ni(2), and one Ni(3) atom.
Ni3Bi2Se2 crystallizes in the monoclinic C2/m space group. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a distorted linear geometry to two equivalent Bi(1), two equivalent Bi(2), and two equivalent Se(1) atoms. Both Ni(1)-Bi(1) bond lengths are 2.85 Å. Both Ni(1)-Bi(2) bond lengths are 2.74 Å. Both Ni(1)-Se(1) bond lengths are 2.29 Å. In the second Ni site, Ni(2) is bonded in a distorted linear geometry to two equivalent Bi(1), two equivalent Bi(2), and two equivalent Se(1) atoms. There is one shorter (2.77 Å) and one longer (2.88 Å) Ni(2)-Bi(1) bond length. There is one shorter (2.74 Å) and one longer (2.76 Å) Ni(2)-Bi(2) bond length. Both Ni(2)-Se(1) bond lengths are 2.29 Å. In the third Ni site, Ni(3) is bonded in a distorted linear geometry to two equivalent Bi(1), two equivalent Bi(2), and two equivalent Se(1) atoms. Both Ni(3)-Bi(1) bond lengths are 2.78 Å. Both Ni(3)-Bi(2) bond lengths are 2.83 Å. Both Ni(3)-Se(1) bond lengths are 2.29 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 6-coordinate geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent Ni(3) atoms. In the second Bi site, Bi(2) is bonded in a 6-coordinate geometry to two equivalent Ni(1), two equivalent Ni(2), and two equivalent Ni(3) atoms. Se(1) is bonded in a distorted T-shaped geometry to one Ni(1), one Ni(2), and one Ni(3) atom.