Redetermination of the crystal structure of tetralithium octafluoridozirconate(IV), Li₄ZrF₈, from single-crystal X-ray data

Abstract

The structure of tetra­lithium octa­fluorido­zirconate has been redetermined by high-resolution single-crystal X-ray diffraction. This result is largely consistent with a prior report, but with significant improvements in precision.

Examination of Molten Salt Reactor Relevant Elements Using Hydrothermal Synthesis

“…When the reaction was repeated with CeO 2 , rather than the expected LiCeF 5 product, Li 4 CeF 8 was isolated instead U, Tb, and Zr , analogues. The structure Li 4 CeF 8 consists of an 8-coordinate Ce 4+ cation in a bicapped trigonal-prismatic geometry with five crystallographically unique fluoride atoms, where one bond is considerably longer, ca.…”

“…The structure Li 4 CeF 8 consists of an 8-coordinate Ce 4+ cation in a bicapped trigonal-prismatic geometry with five crystallographically unique fluoride atoms, where one bond is considerably longer, ca. 0.1 Å, than the other Ce–F bonds, and two 4-coordinate distorted tetrahedral Li + sites, consistent with other Li 4 MF 8 structures. ,,, The average of the four shortest Ce–F bond distances is 2.22(1) Å and ranges from 2.200(5) to 2.249(4) Å with the ninth Ce–F bond of 2.372(4) Å. These distances are similar to the 2.243(8) and 2.24(3) Å average Ce–F distances in CeF 4 and (NH 4 ) 2 CeF 6 , respectively, where (NH 4 ) 2 CeF 6 displays three Ce–F bonds ranging from 2.198(8) to 2.298(8) Å and a fourth bond, 2.318(8) Å, that was not included in the average.…”

Structure, Spectroscopy, and Theoretical Analysis of Zero- and Three-Dimensional Lithium Plutonium Fluorides: Li4PuF8 and LiPuF5

“…No single-crystal structure for Li 4 PuF 8 has been published, although it was previously noted to likely be analogous to the structures that incorporate tetravalent uranium, terbium, and zirconium. ,− The majority of the crystals (estimated 75% by mass) obtained from the aforementioned reactions were of this type, identifiable as thin peach rectangular plates. Li 4 PuF 8 crystallizes in the centrosymmetric orthorhombic space group Pnma .…”

A Molecular Octafluoridoneptunate(IV) Anion in (NH4)4[NpF8] and Theoretical Investigations of the [MF8]4– System (M = Th – Bk)

“…[30][31][32] The bicapped trigonal-prismatic arrangement is observed in Li 4 [MF 8 ] (M = Zr, Ce, Tb, U). [33][34][35][36] Border cases are (NH 4 ) 4 [UF 8 ] and K 5 ThF 9 , in which the [MF 8 ] 4anions are distorted and could either be classified as a squareantiprism or a bicapped trigonal prism. [6,15,16] This is probably also the case for (NH 4 ) 4 [MF 8 ] (M = Ce, Pa, Np, Pu) but only powder diffraction or EXAFS (Np) data has been reported so far and the single-crystal structures have not yet been deter-mined.…”

“…The snub disphenoid arrangement is observed in cyanido complexes such as K 4 [ M (CN) 8 ] · 2H 2 O ( M = Mo, W), ( M (H 2 O) 4 )[W(CN) 8 ] ( M = Ho, Er, Tm, Lu) and ( M (H 2 O) 5 )[W(CN) 8 ] ( M = La, Pr, Nd, Eu, Gd) . The bicapped trigonal‐prismatic arrangement is observed in Li 4 [ M F 8 ] ( M = Zr, Ce, Tb, U) …”