Materials Data on Ca4MgB4(CO9)2 by Materials Project

Ca4MgB4(CO9)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.57 Å. Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six BO4 tetrahedra and edges with two equivalent BO4 tetrahedra. There are two shorter (2.04 Å) and four longer (2.13 Å) Mg–O bond lengths. There are two inequivalent B sites. In the first B site, B is bonded to four O atoms to form BO4 tetrahedra that share corners with two equivalent MgO6 octahedra and corners with two equivalent BO4 tetrahedra. The corner-sharing octahedral tilt angles are 65°. There is two shorter (1.46 Å) and two longer (1.50 Å) B–O bond length. In the second B site, B is bonded to four O atoms to form BO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with two equivalent BO4 tetrahedra, and an edgeedge with one MgO6 octahedra. The corner-sharing octahedral tilt angles are 60°. There are a spread of B–O bond distances ranging from 1.41–1.58 Å. C is bonded in a trigonal planar geometry to three O atoms. There is one shorter (1.28 Å) and two longer (1.30 Å) C–O bond length. There are six inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to two equivalent Ca and one C atom. In the second O site, O is bonded in a distorted single-bond geometry to two equivalent Ca and one B atom. In the third O site, O is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ca and one C atom. In the fourth O site, O is bonded to two equivalent Ca, one Mg, and one B atom to form distorted corner-sharing OCa2MgB tetrahedra. In the fifth O site, O is bonded in a distorted rectangular see-saw-like geometry to one Ca, one Mg, and two B atoms. In the sixth O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom.