DOE OSTI2014
CsU2F9 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one CsU2F9 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded in a 2-coordinate geometry to four F1- atoms. There are a spread of Cs–F bond distances ranging from 2.00–3.12 Å. In the second Cs1+ site, Cs1+ is bonded in a 2-coordinate geometry to seven F1- atoms. There are a spread of Cs–F bond distances ranging from 2.08–3.19 Å. There are four inequivalent U4+ sites. In the first U4+ site, U4+ is bonded in a 1-coordinate geometry to three F1- atoms. There are a spread of U–F bond distances ranging from 1.70–2.34 Å. In the second U4+ site, U4+ is bonded in a 5-coordinate geometry to five F1- atoms. There are a spread of U–F bond distances ranging from 2.01–2.75 Å. In the third U4+ site, U4+ is bonded in a distorted single-bond geometry to five F1- atoms. There are a spread of U–F bond distances ranging from 1.35–2.64 Å. In the fourth U4+ site, U4+ is bonded in a 2-coordinate geometry to three F1- atoms. There are a spread of U–F bond distances ranging from 1.41–2.28 Å. There are eighteen inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to one Cs1+ atom. In the second F1- site, F1- is bonded in a 1-coordinate geometry to one U4+ and one F1- atom. The F–F bond length is 1.51 Å. In the third F1- site, F1- is bonded in a 2-coordinate geometry to two U4+ and one F1- atom. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to two Cs1+ atoms. In the fifth F1- site, F1- is bonded in a 1-coordinate geometry to one Cs1+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one U4+ atom. In the seventh F1- site, F1- is bonded in a distorted single-bond geometry to one Cs1+, one U4+, and one F1- atom. The F–F bond length is 2.10 Å. In the eighth F1- site, F1- is bonded in a 1-coordinate geometry to one Cs1+ and one U4+ atom. In the ninth F1- site, F1- is bonded in a distorted single-bond geometry to one U4+ atom. In the tenth F1- site, F1- is bonded in a 1-coordinate geometry to one Cs1+, two U4+, and three F1- atoms. There are one shorter (2.21 Å) and one longer (2.70 Å) F–F bond lengths. In the eleventh F1- site, F1- is bonded in a single-bond geometry to one U4+ atom. In the twelfth F1- site, F1- is bonded in a single-bond geometry to one U4+ atom. In the thirteenth F1- site, F1- is bonded in a distorted single-bond geometry to one Cs1+ atom. In the fourteenth F1- site, F1- is bonded in a 1-coordinate geometry to one Cs1+ and one F1- atom. In the fifteenth F1- site, F1- is bonded in a single-bond geometry to one U4+ and one F1- atom. In the sixteenth F1- site, F1- is bonded in a 2-coordinate geometry to two U4+ and one F1- atom. The F–F bond length is 1.53 Å. In the seventeenth F1- site, F1- is bonded in a 1-coordinate geometry to one Cs1+, two U4+, and one F1- atom. In the eighteenth F1- site, F1- is bonded in a distorted single-bond geometry to one Cs1+ atom.