Materials Data on Mg3C2O7 by Materials Project
Mg3O(CO3)2 crystallizes in the tetragonal I-42m space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with three equivalent MgO5 trigonal bipyramids and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.94–2.11 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra and edges with four equivalent MgO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.04 Å) and four longer (2.13 Å) Mg–O bond lengths. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.29 Å) and one longer (1.32 Å) C–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a square co-planar geometry to four Mg2+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one C4+ atom. In the third O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Mg2+ and one C4+ atom.