Ba(YbSe2)2 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded in a 6-coordinate geometry to one Se(2), two equivalent Se(1), and three equivalent Se(4) atoms. In the second Yb site, Yb(2) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form edge-sharing YbSe6 octahedra. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to two equivalent Ba(1), one Yb(2), two equivalent Yb(1), and one Se(4) atom. In the second Se site, Se(2) is bonded to two equivalent Ba(1), one Yb(1), and three equivalent Yb(2) atoms to form distorted SeBa2Yb4 octahedra that share corners with four equivalent Se(3)Ba2Yb2 tetrahedra, edges with four equivalent Se(2)Ba2Yb4 octahedra, and edges with three equivalent Se(3)Ba2Yb2 tetrahedra. In the third Se site, Se(3) is bonded to two equivalent Ba(1) and two equivalent Yb(2) atoms to form distorted SeBa2Yb2 tetrahedra that share corners with four equivalent Se(2)Ba2Yb4 octahedra, corners with four equivalent Se(3)Ba2Yb2 tetrahedra, and edges with three equivalent Se(2)Ba2Yb4 octahedra. The corner-sharing octahedral tilt angles range from 13-50°. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to two equivalent Ba(1), three equivalent Yb(1), and one Se(1) atom.
Ba(YbSe2)2 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. Both Ba(1)-Se(1) bond lengths are 3.59 Å. Both Ba(1)-Se(2) bond lengths are 3.40 Å. There is one shorter (3.19 Å) and one longer (3.21 Å) Ba(1)-Se(3) bond length. Both Ba(1)-Se(4) bond lengths are 3.47 Å. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded in a 6-coordinate geometry to one Se(2), two equivalent Se(1), and three equivalent Se(4) atoms. The Yb(1)-Se(2) bond length is 2.89 Å. Both Yb(1)-Se(1) bond lengths are 2.83 Å. There is one shorter (3.00 Å) and two longer (3.05 Å) Yb(1)-Se(4) bond lengths. In the second Yb site, Yb(2) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form edge-sharing YbSe6 octahedra. The Yb(2)-Se(1) bond length is 3.03 Å. Both Yb(2)-Se(3) bond lengths are 2.85 Å. There is one shorter (2.92 Å) and two longer (3.18 Å) Yb(2)-Se(2) bond lengths. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to two equivalent Ba(1), one Yb(2), two equivalent Yb(1), and one Se(4) atom. The Se(1)-Se(4) bond length is 2.56 Å. In the second Se site, Se(2) is bonded to two equivalent Ba(1), one Yb(1), and three equivalent Yb(2) atoms to form distorted SeBa2Yb4 octahedra that share corners with four equivalent Se(3)Ba2Yb2 tetrahedra, edges with four equivalent Se(2)Ba2Yb4 octahedra, and edges with three equivalent Se(3)Ba2Yb2 tetrahedra. In the third Se site, Se(3) is bonded to two equivalent Ba(1) and two equivalent Yb(2) atoms to form distorted SeBa2Yb2 tetrahedra that share corners with four equivalent Se(2)Ba2Yb4 octahedra, corners with four equivalent Se(3)Ba2Yb2 tetrahedra, and edges with three equivalent Se(2)Ba2Yb4 octahedra. The corner-sharing octahedral tilt angles range from 13-50°. In the fourth Se site, Se(4) is bonded in a 6-coordinate geometry to two equivalent Ba(1), three equivalent Yb(1), and one Se(1) atom.