EuNi9Ge4 crystallizes in the tetragonal I4/mcm space group. Eu(1) is bonded in a 24-coordinate geometry to eight equivalent Ni(1), eight equivalent Ni(2), and eight equivalent Ge(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(2), three equivalent Ni(1), and four equivalent Ge(1) atoms to form distorted NiEu2Ni6Ge4 cuboctahedra that share  a cornercorner with one Ni(3)Ni8Ge4 cuboctahedra, corners with eleven equivalent Ni(1)Eu2Ni6Ge4 cuboctahedra, faces with two equivalent Ni(3)Ni8Ge4 cuboctahedra, and faces with seven equivalent Ni(1)Eu2Ni6Ge4 cuboctahedra. In the second Ni site, Ni(2) is bonded in a 4-coordinate geometry to two equivalent Eu(1), one Ni(3), two equivalent Ni(1), and four equivalent Ge(1) atoms. In the third Ni site, Ni(3) is bonded to four equivalent Ni(1), four equivalent Ni(2), and four equivalent Ge(1) atoms to form a mixture of face and corner-sharing NiNi8Ge4 cuboctahedra. Ge(1) is bonded in a 11-coordinate geometry to two equivalent Eu(1), one Ni(3), four equivalent Ni(1), and four equivalent Ni(2) atoms.
EuNi9Ge4 crystallizes in the tetragonal I4/mcm space group. Eu(1) is bonded in a 24-coordinate geometry to eight equivalent Ni(1), eight equivalent Ni(2), and eight equivalent Ge(1) atoms. All Eu(1)-Ni(1) bond lengths are 3.43 Å. All Eu(1)-Ni(2) bond lengths are 3.26 Å. All Eu(1)-Ge(1) bond lengths are 3.32 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(2), three equivalent Ni(1), and four equivalent Ge(1) atoms to form distorted NiEu2Ni6Ge4 cuboctahedra that share  a cornercorner with one Ni(3)Ni8Ge4 cuboctahedra, corners with eleven equivalent Ni(1)Eu2Ni6Ge4 cuboctahedra, faces with two equivalent Ni(3)Ni8Ge4 cuboctahedra, and faces with seven equivalent Ni(1)Eu2Ni6Ge4 cuboctahedra. The Ni(1)-Ni(3) bond length is 2.43 Å. Both Ni(1)-Ni(2) bond lengths are 2.60 Å. There are two shorter (2.42 Å) and one longer (2.59 Å) Ni(1)-Ni(1) bond length. There are two shorter (2.54 Å) and two longer (2.61 Å) Ni(1)-Ge(1) bond lengths. In the second Ni site, Ni(2) is bonded in a 4-coordinate geometry to two equivalent Eu(1), one Ni(3), two equivalent Ni(1), and four equivalent Ge(1) atoms. The Ni(2)-Ni(3) bond length is 2.57 Å. There are two shorter (2.39 Å) and two longer (2.51 Å) Ni(2)-Ge(1) bond lengths. In the third Ni site, Ni(3) is bonded to four equivalent Ni(1), four equivalent Ni(2), and four equivalent Ge(1) atoms to form a mixture of face and corner-sharing NiNi8Ge4 cuboctahedra. All Ni(3)-Ge(1) bond lengths are 2.45 Å. Ge(1) is bonded in a 11-coordinate geometry to two equivalent Eu(1), one Ni(3), four equivalent Ni(1), and four equivalent Ni(2) atoms.