ULM-18, a Fluorinated Gallium Phosphate with Perforated Layers:  XRD and NMR, Structure Determination, and HF Localization in a D4R

Abstract

Ga 4 (PO 4 ) 5 HF-1.5 N 2 C 6 H 18 -H 2 O (or ULM-18) is an oxyfluorinated gallium phosphate obtained by hydrothermal synthesis using N,N,N′,N′-tetramethylethylenediamine as a template. The structure is described in the triclinic space group P-1 (n°2) with a ) 8.5264(7) Å, b ) 9.2512(7) Å, c ) 17.870(2) Å, R ) 101.742-(7)°, ) 99.137(7)°, γ ) 87.020(6)°, V ) 1362.3(2) Å 3 , and Z ) 2. The two-dimensional framework is built up from sheets containing double four-ring units (D4R) connected by PO 4 tetrahedra. Along [010] and [011], 8-ring channels makes the layers hollow. The D4R units consist of four PO 4 tetrahedra, three GaO 4 F trigonal bipyramids, and one GaO 5 trigonal bipyramid. The D4R structure contains a templating fluorine. 19 F MAS at high speed and 71 Ga DOR lead to elucidation of their environment. 31 P NMR MAS, RFDR, and double-quanta analyses are used to assign phosphorus. 31 P-{ 1 H} CPMAS shows that an hydrogen is inside the D4R unit. Those features together make this building unit a quite unusual D4R conformation. For sake of the rationalization of the framework construction, this D4R is compared to known MPO D4R (M ) Al, Ga, Fe, V, Co), and the results of this comparison suggest a general scheme for proton insertion in the structure.

Crystalline oxyfluorinated open-framework compounds: Silicates, metal phosphates, metal fluorides and metal-organic frameworks (MOF)

“…A thorough analysis of the unusual configuration of fluorine within the D4R cavity has indicated that this atom is often off-centered and preferentially interacts with one, two or three gallium atoms, inducing geometrical distortions of the gallium coordination polyhedra (the environment becomes a trigonal bipyramid instead of a tetrahedron). In the gallium phosphate ULM-18, detailed NMR experiment [63] has also shown the occurrence of an isolated ''HF'' molecule inserted in the D4R instead of the expected fluoride anions F À . This unique configuration was investigated by means of DFT calculations, which confirm the existence of the H-F molecule within the D4R [64].…”

Solvothermal Preparation, Crystal Structure, and Photoluminescence of a Cadmium Compound With a Two-Dimensional Supramolecular Layer

“…In order to keep charge balance the bridging Cl1 atom must be HCl molecule, as the cases found in the literature. [12][13][14] Therefore, the Cd 2 Cl 7 dimer should be CdCl 3 -HCl-CdCl 3 moiety. The result of the bond valence calculation reveals that all the cadmium atoms are in C2 oxidation state (Cd1: 2.154, Cd2: 2.278).…”

Germanates of 1D Chains, 2D Layers, and 3D Frameworks Built from Ge–O Clusters by Using Metal‐Complex Templates: Host–Guest Symmetry and Chirality Transfer

“…Whereas all the Ge polyhedra are connected to each other by their vertices, the two trigonal bipyramids are linked by a common edge. The Ge 7 X 19 cluster unit can also be described as a D4R unit, which is present in zeolites, AlPOs,37–40 and some germanates,8c, 29, 41, 42 with two neighboring tetrahedral atoms replaced by one capping octahedral Ge atom. The location of the central tricoordinated oxygen atom within the cluster unit is similar to that of a fluorine or an oxygen atom that is typically observed within the D4R cage.…”