Materials Data on Sr2B8Ru7 by Materials Project
Sr2Ru7B8 crystallizes in the tetragonal P4_2/m space group. The structure is three-dimensional. Sr2+ is bonded in a 11-coordinate geometry to one Sr2+ and ten B+2.25- atoms. The Sr–Sr bond length is 3.32 Å. There are a spread of Sr–B bond distances ranging from 3.14–3.38 Å. There are three inequivalent Ru2+ sites. In the first Ru2+ site, Ru2+ is bonded to six B+2.25- atoms to form RuB6 octahedra that share corners with four RuB6 octahedra, a cornercorner with one RuB4 trigonal pyramid, edges with three RuB6 octahedra, an edgeedge with one RuB4 trigonal pyramid, and faces with four RuB6 octahedra. The corner-sharing octahedra tilt angles range from 42–45°. There are a spread of Ru–B bond distances ranging from 2.14–2.36 Å. In the second Ru2+ site, Ru2+ is bonded to six B+2.25- atoms to form RuB6 octahedra that share corners with four equivalent RuB6 octahedra, corners with two equivalent RuB4 trigonal pyramids, edges with six RuB6 octahedra, and faces with two equivalent RuB6 octahedra. The corner-sharing octahedral tilt angles are 42°. There are a spread of Ru–B bond distances ranging from 2.15–2.26 Å. In the third Ru2+ site, Ru2+ is bonded to four equivalent B+2.25- atoms to form a mixture of distorted corner and edge-sharing RuB4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 38–42°. All Ru–B bond lengths are 2.08 Å. There are three inequivalent B+2.25- sites. In the first B+2.25- site, B+2.25- is bonded in a 7-coordinate geometry to two equivalent Sr2+, four Ru2+, and three B+2.25- atoms. There is two shorter (1.79 Å) and one longer (1.81 Å) B–B bond length. In the second B+2.25- site, B+2.25- is bonded in a 6-coordinate geometry to three equivalent Sr2+, five Ru2+, and one B+2.25- atom. In the third B+2.25- site, B+2.25- is bonded in a 7-coordinate geometry to two equivalent Sr2+, six Ru2+, and one B+2.25- atom. The B–B bond length is 1.85 Å.