A New Nanometer-Sized Ga(III)-Oxyhydroxide Cation

Abstract

A new 30-center Ga(III)-oxy-hydroxide cation cluster was synthesized by hydrolysis of an aqueous GaCl3 solution near pH = 2.5 and crystallized using 2,6-napthalene disulfonate (NDS). The cluster has 30 metal centers and a nominal stoichiometry: [Ga30(μ4-O)12(μ3-O)4(μ3-OH)4(μ2-OH)42(H2O)16](2,6-NDS)6, where 2,6-NDS = 2,6-napthalene disulfonate This cluster augments the very small library of Group 13 clusters that have been isolated from aqueous solution and closely resembles one other Ga(III) cluster with 32 metal centers that had been isolated using curcurbit ligands. These clusters have uncommon linked Ga(O)4 centers and sets of both protonated and unprotonated μ3-oxo.

Structural Chemistry of Giant Metal Based Supramolecules

“…Back in 2015, the same group also obtained the 2,6-napthalene disulfonate salt of the [Ga 30 O 16 (OH) 46 (H 2 O) 16 ] 12+ cation (Table 4). 172 An original approach to the crystallization of similar complexes using organic cavitand cucurbituril was developed by O. A. Gerasko and V. P. Fedin (Inst.…”

Pair distribution function and 71Ga NMR study of aqueous Ga3+ complexes

“…28 Several studies have sought to crystallise the Ga 13 Keggin structure, but these resulted in different polyoxogallate clusters of varying sizes Ga 8 , Ga 9 , Ga 12 , planar Ga 13 , Ga 30 and Ga 32 (full nominal composition in Table S4). [8][9][10][11][12][13] Importantly, no study specifically has observed the atomic positions in the suggested Ga 13 Keggin structure.…”

“…The misinterpretation presumably is due to weak experimental evidence in combination with a tendency to correlate Ga data with the well-known Al 13 Keggin structure. It should be noted that the Ga 30 and Ga 32 moieties have been observed in crystal structures, 11,13 whereas the Ga 13 structure has never been firmly demonstrated.…”

“…As an example several gallium structures of varying sizes and coordination have been determined using single-crystal X-ray diffraction. [5][6][7][8][9][10][11][12][13] While solid state structures presumably have given insight into unknown solvated structures, many structures remain impossible to crystallize and fundamental uncertainty remains due to the structural perturbations caused by the solvent and the highly dynamic character of a solution. Recent developments of the total scattering (TS) and pair distribution function (PDF) techniques are changing the scientific landscape, as the accessibility and quality of data and modelling possibilities have increased enormously.…”

“…[30][31][32] Several new gallium clusters have been discovered by single-crystal X-ray diffraction in the pursuit to confirm the presence of the Keggin structure, but structural information of the actual Ga Keggin ion remains elusive. [8][9][10][11][12][13] In general, characterisation of aqueous gallium chemistry is less extensive than for the well-studied aluminium system, and group trends in the periodic table between the two systems have guided the analysis of various data on gallium systems and suggested similar structures. [27][28][29] Here we use X-ray TS and subsequent PDF analysis in combination with 71 Ga NMR to investigate the atomic structures of aqueous Ga 3+ complexes across the entire pH range, for three different counter ions (nitrate, chloride, sulfate) and Ga 3+ concentrations in the 0.5 -2 M range.…”