Materials Data on MgU2(SiO9)2 by Materials Project
MgU2(SiO9)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Mg is bonded in a linear geometry to six O atoms. There are two shorter (1.83 Å) and four longer (2.73 Å) Mg–O bond lengths. U is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of U–O bond distances ranging from 1.82–2.54 Å. Si is bonded in a tetrahedral geometry to four O atoms. There are a spread of Si–O bond distances ranging from 1.59–1.66 Å. There are seven inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one U atom. In the second O site, O is bonded in a single-bond geometry to one U atom. In the third O site, O is bonded in a bent 150 degrees geometry to one U and one Si atom. In the fourth O site, O is bonded in a linear geometry to one Mg and one Si atom. In the fifth O site, O is bonded in a 1-coordinate geometry to two equivalent U and one Si atom. In the sixth O site, O is bonded in a bent 150 degrees geometry to one Mg and one O atom. The O–O bond length is 1.29 Å. In the seventh O site, O is bonded in a bent 120 degrees geometry to two equivalent O atoms.