DOE OSTI2020
La3(AlI)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent La sites. In the first La site, La is bonded in a 2-coordinate geometry to four Al and two equivalent I atoms. There are a spread of La–Al bond distances ranging from 3.21–3.33 Å. Both La–I bond lengths are 3.23 Å. In the second La site, La is bonded to three Al and four I atoms to form distorted edge-sharing LaAl3I4 pentagonal bipyramids. There are two shorter (3.19 Å) and one longer (3.31 Å) La–Al bond lengths. There are a spread of La–I bond distances ranging from 3.32–3.54 Å. In the third La site, La is bonded in a 8-coordinate geometry to six Al and three I atoms. There are a spread of La–Al bond distances ranging from 3.28–3.58 Å. There are one shorter (3.45 Å) and two longer (3.47 Å) La–I bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded in a 9-coordinate geometry to six La and three Al atoms. There are one shorter (2.57 Å) and two longer (2.63 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 9-coordinate geometry to seven La and two equivalent Al atoms. There are two inequivalent I sites. In the first I site, I is bonded in a distorted rectangular see-saw-like geometry to four La atoms. In the second I site, I is bonded to five La atoms to form distorted edge-sharing ILa5 square pyramids.