EuNi9In2 crystallizes in the tetragonal P4/mbm space group. Eu(1) is bonded in a 20-coordinate geometry to eight equivalent Ni(1), eight equivalent Ni(2), and four equivalent In(1) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Eu(1), one Ni(3), two equivalent Ni(1), four equivalent Ni(2), and three equivalent In(1) atoms to form distorted NiEu2In3Ni7 cuboctahedra that share  a cornercorner with one Ni(3)In4Ni8 cuboctahedra, corners with six equivalent Ni(2)Eu2In2Ni8 cuboctahedra, corners with eleven equivalent Ni(1)Eu2In3Ni7 cuboctahedra, edges with four equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with five equivalent Ni(1)Eu2In3Ni7 cuboctahedra, faces with three equivalent Ni(3)In4Ni8 cuboctahedra, faces with seven equivalent Ni(1)Eu2In3Ni7 cuboctahedra, and faces with ten equivalent Ni(2)Eu2In2Ni8 cuboctahedra. In the second Ni site, Ni(2) is bonded to two equivalent Eu(1), one Ni(3), three equivalent Ni(2), four equivalent Ni(1), and two equivalent In(1) atoms to form distorted NiEu2In2Ni8 cuboctahedra that share corners with three equivalent Ni(3)In4Ni8 cuboctahedra, corners with six equivalent Ni(1)Eu2In3Ni7 cuboctahedra, corners with eleven equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with two equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with four equivalent Ni(1)Eu2In3Ni7 cuboctahedra, faces with two equivalent Ni(3)In4Ni8 cuboctahedra, faces with seven equivalent Ni(2)Eu2In2Ni8 cuboctahedra, and faces with ten equivalent Ni(1)Eu2In3Ni7 cuboctahedra. In the third Ni site, Ni(3) is bonded to four equivalent Ni(1), four equivalent Ni(2), and four equivalent In(1) atoms to form NiIn4Ni8 cuboctahedra that share corners with four equivalent Ni(1)Eu2In3Ni7 cuboctahedra, corners with twelve equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with two equivalent Ni(3)In4Ni8 cuboctahedra, faces with eight equivalent Ni(2)Eu2In2Ni8 cuboctahedra, and faces with twelve equivalent Ni(1)Eu2In3Ni7 cuboctahedra. In(1) is bonded in a 15-coordinate geometry to two equivalent Eu(1), two equivalent Ni(3), four equivalent Ni(2), six equivalent Ni(1), and one In(1) atom.
EuNi9In2 crystallizes in the tetragonal P4/mbm space group. Eu(1) is bonded in a 20-coordinate geometry to eight equivalent Ni(1), eight equivalent Ni(2), and four equivalent In(1) atoms. All Eu(1)-Ni(1) bond lengths are 3.30 Å. All Eu(1)-Ni(2) bond lengths are 3.05 Å. All Eu(1)-In(1) bond lengths are 3.29 Å. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent Eu(1), one Ni(3), two equivalent Ni(1), four equivalent Ni(2), and three equivalent In(1) atoms to form distorted NiEu2In3Ni7 cuboctahedra that share  a cornercorner with one Ni(3)In4Ni8 cuboctahedra, corners with six equivalent Ni(2)Eu2In2Ni8 cuboctahedra, corners with eleven equivalent Ni(1)Eu2In3Ni7 cuboctahedra, edges with four equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with five equivalent Ni(1)Eu2In3Ni7 cuboctahedra, faces with three equivalent Ni(3)In4Ni8 cuboctahedra, faces with seven equivalent Ni(1)Eu2In3Ni7 cuboctahedra, and faces with ten equivalent Ni(2)Eu2In2Ni8 cuboctahedra. The Ni(1)-Ni(3) bond length is 2.41 Å. Both Ni(1)-Ni(1) bond lengths are 2.44 Å. There are two shorter (2.49 Å) and two longer (2.53 Å) Ni(1)-Ni(2) bond lengths. There is one shorter (2.64 Å) and two longer (2.82 Å) Ni(1)-In(1) bond lengths. In the second Ni site, Ni(2) is bonded to two equivalent Eu(1), one Ni(3), three equivalent Ni(2), four equivalent Ni(1), and two equivalent In(1) atoms to form distorted NiEu2In2Ni8 cuboctahedra that share corners with three equivalent Ni(3)In4Ni8 cuboctahedra, corners with six equivalent Ni(1)Eu2In3Ni7 cuboctahedra, corners with eleven equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with two equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with four equivalent Ni(1)Eu2In3Ni7 cuboctahedra, faces with two equivalent Ni(3)In4Ni8 cuboctahedra, faces with seven equivalent Ni(2)Eu2In2Ni8 cuboctahedra, and faces with ten equivalent Ni(1)Eu2In3Ni7 cuboctahedra. The Ni(2)-Ni(3) bond length is 2.47 Å. There are two shorter (2.59 Å) and one longer (2.65 Å) Ni(2)-Ni(2) bond length. Both Ni(2)-In(1) bond lengths are 2.85 Å. In the third Ni site, Ni(3) is bonded to four equivalent Ni(1), four equivalent Ni(2), and four equivalent In(1) atoms to form NiIn4Ni8 cuboctahedra that share corners with four equivalent Ni(1)Eu2In3Ni7 cuboctahedra, corners with twelve equivalent Ni(2)Eu2In2Ni8 cuboctahedra, edges with two equivalent Ni(3)In4Ni8 cuboctahedra, faces with eight equivalent Ni(2)Eu2In2Ni8 cuboctahedra, and faces with twelve equivalent Ni(1)Eu2In3Ni7 cuboctahedra. All Ni(3)-In(1) bond lengths are 2.85 Å. In(1) is bonded in a 15-coordinate geometry to two equivalent Eu(1), two equivalent Ni(3), four equivalent Ni(2), six equivalent Ni(1), and one In(1) atom. The In(1)-In(1) bond length is 2.93 Å.