BaCu2Se2 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 16-coordinate geometry to four equivalent Cu(1), five equivalent Cu(2), three equivalent Se(1), and four equivalent Se(2) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent Ba(1), one Se(1), and three equivalent Se(2) atoms to form distorted CuBa4Se4 tetrahedra that share corners with six equivalent Cu(1)Ba4Se4 tetrahedra, corners with eight equivalent Cu(2)Ba5Se4 tetrahedra, edges with two equivalent Cu(1)Ba4Se4 tetrahedra, faces with two equivalent Cu(1)Ba4Se4 tetrahedra, and faces with six equivalent Cu(2)Ba5Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to five equivalent Ba(1), one Se(2), and three equivalent Se(1) atoms to form distorted CuBa5Se4 tetrahedra that share corners with eight equivalent Cu(1)Ba4Se4 tetrahedra, corners with eight equivalent Cu(2)Ba5Se4 tetrahedra, edges with two equivalent Cu(2)Ba5Se4 tetrahedra, faces with four equivalent Cu(2)Ba5Se4 tetrahedra, and faces with six equivalent Cu(1)Ba4Se4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to three equivalent Ba(1), one Cu(1), and three equivalent Cu(2) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to four equivalent Ba(1), one Cu(2), and three equivalent Cu(1) atoms.
BaCu2Se2 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 16-coordinate geometry to four equivalent Cu(1), five equivalent Cu(2), three equivalent Se(1), and four equivalent Se(2) atoms. There are a spread of Ba(1)-Cu(1) bond distances ranging from 3.42-3.59 Å. There are a spread of Ba(1)-Cu(2) bond distances ranging from 3.59-3.67 Å. There is one shorter (3.22 Å) and two longer (3.25 Å) Ba(1)-Se(1) bond lengths. There are two shorter (3.41 Å) and two longer (3.42 Å) Ba(1)-Se(2) bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent Ba(1), one Se(1), and three equivalent Se(2) atoms to form distorted CuBa4Se4 tetrahedra that share corners with six equivalent Cu(1)Ba4Se4 tetrahedra, corners with eight equivalent Cu(2)Ba5Se4 tetrahedra, edges with two equivalent Cu(1)Ba4Se4 tetrahedra, faces with two equivalent Cu(1)Ba4Se4 tetrahedra, and faces with six equivalent Cu(2)Ba5Se4 tetrahedra. The Cu(1)-Se(1) bond length is 2.51 Å. There is one shorter (2.47 Å) and two longer (2.57 Å) Cu(1)-Se(2) bond lengths. In the second Cu site, Cu(2) is bonded to five equivalent Ba(1), one Se(2), and three equivalent Se(1) atoms to form distorted CuBa5Se4 tetrahedra that share corners with eight equivalent Cu(1)Ba4Se4 tetrahedra, corners with eight equivalent Cu(2)Ba5Se4 tetrahedra, edges with two equivalent Cu(2)Ba5Se4 tetrahedra, faces with four equivalent Cu(2)Ba5Se4 tetrahedra, and faces with six equivalent Cu(1)Ba4Se4 tetrahedra. The Cu(2)-Se(2) bond length is 2.48 Å. There are two shorter (2.46 Å) and one longer (2.62 Å) Cu(2)-Se(1) bond length. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 7-coordinate geometry to three equivalent Ba(1), one Cu(1), and three equivalent Cu(2) atoms. In the second Se site, Se(2) is bonded in a 8-coordinate geometry to four equivalent Ba(1), one Cu(2), and three equivalent Cu(1) atoms.