BaNi2Al9 crystallizes in the hexagonal P6/mmm space group. Ba(1) is bonded to twelve equivalent Al(2) atoms to form face-sharing BaAl12 cuboctahedra. Ni(1) is bonded in a 9-coordinate geometry to three equivalent Al(1) and six equivalent Al(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a linear geometry to two equivalent Ni(1) and eight equivalent Al(2) atoms. In the second Al site, Al(2) is bonded in a 12-coordinate geometry to two equivalent Ba(1), two equivalent Ni(1), four equivalent Al(1), and four equivalent Al(2) atoms.
BaNi2Al9 crystallizes in the hexagonal P6/mmm space group. Ba(1) is bonded to twelve equivalent Al(2) atoms to form face-sharing BaAl12 cuboctahedra. All Ba(1)-Al(2) bond lengths are 3.55 Å. Ni(1) is bonded in a 9-coordinate geometry to three equivalent Al(1) and six equivalent Al(2) atoms. All Ni(1)-Al(1) bond lengths are 2.28 Å. All Ni(1)-Al(2) bond lengths are 2.56 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a linear geometry to two equivalent Ni(1) and eight equivalent Al(2) atoms. All Al(1)-Al(2) bond lengths are 2.84 Å. In the second Al site, Al(2) is bonded in a 12-coordinate geometry to two equivalent Ba(1), two equivalent Ni(1), four equivalent Al(1), and four equivalent Al(2) atoms. There are two shorter (2.81 Å) and two longer (2.94 Å) Al(2)-Al(2) bond lengths.