Er4NiB13 crystallizes in the tetragonal P4/mnc space group. Er(1) is bonded in a 16-coordinate geometry to one Ni(1), one B(3), six equivalent B(2), and eight equivalent B(1) atoms. Ni(1) is bonded to four equivalent Er(1) and eight equivalent B(1) atoms to form NiEr4B8 cuboctahedra that share corners with four equivalent B(3)Er4B8 cuboctahedra and faces with two equivalent B(3)Er4B8 cuboctahedra. There are three inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to four equivalent Er(1), one Ni(1), one B(2), one B(3), and two equivalent B(1) atoms. In the second B site, B(2) is bonded in a 9-coordinate geometry to six equivalent Er(1), one B(2), and two equivalent B(1) atoms. In the third B site, B(3) is bonded to four equivalent Er(1) and eight equivalent B(1) atoms to form BEr4B8 cuboctahedra that share corners with four equivalent Ni(1)Er4B8 cuboctahedra and faces with two equivalent Ni(1)Er4B8 cuboctahedra.
Er4NiB13 crystallizes in the tetragonal P4/mnc space group. Er(1) is bonded in a 16-coordinate geometry to one Ni(1), one B(3), six equivalent B(2), and eight equivalent B(1) atoms. The Er(1)-Ni(1) bond length is 2.69 Å. The Er(1)-B(3) bond length is 2.64 Å. There are a spread of Er(1)-B(2) bond distances ranging from 2.70-2.89 Å. There are a spread of Er(1)-B(1) bond distances ranging from 2.54-2.70 Å. Ni(1) is bonded to four equivalent Er(1) and eight equivalent B(1) atoms to form NiEr4B8 cuboctahedra that share corners with four equivalent B(3)Er4B8 cuboctahedra and faces with two equivalent B(3)Er4B8 cuboctahedra. All Ni(1)-B(1) bond lengths are 2.17 Å. There are three inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to four equivalent Er(1), one Ni(1), one B(2), one B(3), and two equivalent B(1) atoms. The B(1)-B(2) bond length is 1.77 Å. The B(1)-B(3) bond length is 2.10 Å. Both B(1)-B(1) bond lengths are 1.81 Å. In the second B site, B(2) is bonded in a 9-coordinate geometry to six equivalent Er(1), one B(2), and two equivalent B(1) atoms. The B(2)-B(2) bond length is 1.89 Å. In the third B site, B(3) is bonded to four equivalent Er(1) and eight equivalent B(1) atoms to form BEr4B8 cuboctahedra that share corners with four equivalent Ni(1)Er4B8 cuboctahedra and faces with two equivalent Ni(1)Er4B8 cuboctahedra.