DOE OSTI2020
Ca7(H6Cl)2 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to nine H1- atoms. There are three shorter (2.23 Å) and six longer (2.53 Å) Ca–H bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to seven H1- and two equivalent Cl1- atoms. There are a spread of Ca–H bond distances ranging from 2.24–2.62 Å. Both Ca–Cl bond lengths are 2.92 Å. In the third Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to seven H1- and two equivalent Cl1- atoms. There are a spread of Ca–H bond distances ranging from 2.30–2.40 Å. Both Ca–Cl bond lengths are 2.96 Å. There are four inequivalent H1- sites. In the first H1- site, H1- is bonded to four Ca2+ atoms to form HCa4 tetrahedra that share corners with four ClCa6 pentagonal pyramids, corners with two equivalent HCa5 square pyramids, corners with ten HCa4 tetrahedra, an edgeedge with one ClCa6 pentagonal pyramid, edges with four equivalent HCa5 square pyramids, and edges with three HCa4 tetrahedra. In the second H1- site, H1- is bonded to four Ca2+ atoms to form HCa4 tetrahedra that share corners with two equivalent ClCa6 pentagonal pyramids, corners with two equivalent HCa5 square pyramids, corners with twelve HCa4 tetrahedra, edges with three ClCa6 pentagonal pyramids, edges with two equivalent HCa5 square pyramids, and edges with three HCa4 tetrahedra. In the third H1- site, H1- is bonded to five Ca2+ atoms to form distorted HCa5 square pyramids that share corners with four ClCa6 pentagonal pyramids, corners with four equivalent HCa5 square pyramids, corners with eight HCa4 tetrahedra, an edgeedge with one ClCa6 pentagonal pyramid, edges with four equivalent HCa5 square pyramids, and edges with seven HCa4 tetrahedra. In the fourth H1- site, H1- is bonded to four Ca2+ atoms to form HCa4 tetrahedra that share corners with two equivalent ClCa6 pentagonal pyramids, corners with four equivalent HCa5 square pyramids, corners with ten HCa4 tetrahedra, edges with three ClCa6 pentagonal pyramids, an edgeedge with one HCa5 square pyramid, and edges with four HCa4 tetrahedra. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded to six equivalent Ca2+ atoms to form distorted ClCa6 pentagonal pyramids that share corners with six equivalent HCa5 square pyramids, corners with twelve HCa4 tetrahedra, edges with twelve HCa4 tetrahedra, and faces with two equivalent ClCa6 pentagonal pyramids. In the second Cl1- site, Cl1- is bonded to six equivalent Ca2+ atoms to form distorted ClCa6 pentagonal pyramids that share corners with six equivalent HCa5 square pyramids, corners with twelve HCa4 tetrahedra, edges with three equivalent HCa5 square pyramids, edges with nine HCa4 tetrahedra, and faces with two equivalent ClCa6 pentagonal pyramids.