Materials Data on Mg4Al2H12CO18 by Materials Project
(Mg2Al(HO)6)4(CO3)2(O2)3 crystallizes in the trigonal P31m space group. The structure is two-dimensional and consists of one carbonic acid molecule; three water molecules; and two Mg2Al(HO)6 sheets oriented in the (0, 0, 1) direction. In each Mg2Al(HO)6 sheet, Mg is bonded to six O atoms to form MgO6 octahedra that share edges with three equivalent MgO6 octahedra and edges with three equivalent AlO6 octahedra. There are three shorter (2.09 Å) and three longer (2.10 Å) Mg–O bond lengths. Al is bonded to six O atoms to form AlO6 octahedra that share edges with six equivalent MgO6 octahedra. All Al–O bond lengths are 1.93 Å. There are two inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. There are two inequivalent O sites. In the first O site, O is bonded in a 1-coordinate geometry to two equivalent Mg, one Al, and one H atom. In the second O site, O is bonded in a 1-coordinate geometry to two equivalent Mg, one Al, and one H atom.