LaNi9Si4 crystallizes in the tetragonal I4/mcm space group. La(1) is bonded in a 24-coordinate geometry to eight equivalent Ni(1), eight equivalent Ni(2), and eight equivalent Si(1) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent La(1), one Ni(3), two equivalent Ni(2), three equivalent Ni(1), and four equivalent Si(1) atoms to form NiLa2Si4Ni6 cuboctahedra that share  a cornercorner with one Ni(3)Si4Ni8 cuboctahedra, corners with eleven equivalent Ni(1)La2Si4Ni6 cuboctahedra, faces with two equivalent Ni(3)Si4Ni8 cuboctahedra, and faces with seven equivalent Ni(1)La2Si4Ni6 cuboctahedra. In the second Ni site, Ni(2) is bonded in a 11-coordinate geometry to two equivalent La(1), one Ni(3), two equivalent Ni(1), two equivalent Ni(2), and four equivalent Si(1) atoms. In the third Ni site, Ni(3) is bonded to four equivalent Ni(1), four equivalent Ni(2), and four equivalent Si(1) atoms to form a mixture of corner and face-sharing NiSi4Ni8 cuboctahedra. Si(1) is bonded in a 12-coordinate geometry to two equivalent La(1), one Ni(3), four equivalent Ni(1), four equivalent Ni(2), and one Si(1) atom.
LaNi9Si4 crystallizes in the tetragonal I4/mcm space group. La(1) is bonded in a 24-coordinate geometry to eight equivalent Ni(1), eight equivalent Ni(2), and eight equivalent Si(1) atoms. All La(1)-Ni(1) bond lengths are 3.32 Å. All La(1)-Ni(2) bond lengths are 3.16 Å. All La(1)-Si(1) bond lengths are 3.28 Å. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent La(1), one Ni(3), two equivalent Ni(2), three equivalent Ni(1), and four equivalent Si(1) atoms to form NiLa2Si4Ni6 cuboctahedra that share  a cornercorner with one Ni(3)Si4Ni8 cuboctahedra, corners with eleven equivalent Ni(1)La2Si4Ni6 cuboctahedra, faces with two equivalent Ni(3)Si4Ni8 cuboctahedra, and faces with seven equivalent Ni(1)La2Si4Ni6 cuboctahedra. The Ni(1)-Ni(3) bond length is 2.38 Å. Both Ni(1)-Ni(2) bond lengths are 2.53 Å. There are two shorter (2.39 Å) and one longer (2.52 Å) Ni(1)-Ni(1) bond length. There are two shorter (2.46 Å) and two longer (2.51 Å) Ni(1)-Si(1) bond lengths. In the second Ni site, Ni(2) is bonded in a 11-coordinate geometry to two equivalent La(1), one Ni(3), two equivalent Ni(1), two equivalent Ni(2), and four equivalent Si(1) atoms. The Ni(2)-Ni(3) bond length is 2.56 Å. Both Ni(2)-Ni(2) bond lengths are 2.54 Å. There are a spread of Ni(2)-Si(1) bond distances ranging from 2.30-2.51 Å. In the third Ni site, Ni(3) is bonded to four equivalent Ni(1), four equivalent Ni(2), and four equivalent Si(1) atoms to form a mixture of corner and face-sharing NiSi4Ni8 cuboctahedra. All Ni(3)-Si(1) bond lengths are 2.32 Å. Si(1) is bonded in a 12-coordinate geometry to two equivalent La(1), one Ni(3), four equivalent Ni(1), four equivalent Ni(2), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.68 Å.