Synthesis of the Hydroxide Cluster [Al₁₃(μ₃-OH)₆(μ-OH)₁₈(H₂O)₂₄]¹⁵⁺ from an Aqueous Solution

Abstract

A scalable synthesis of the "flat" tridecameric inorganic cluster [Al(13)(μ(3)-OH)(6)(μ-OH)(18)(H(2)O)(24)](15+) has been realized by treating an aqueous aluminum nitrate solution with a zinc-metal powder at room temperature. Single crystals and polycrystalline samples are readily obtained in yields exceeding 55% relative to the starting reagent Al(NO(3))(3). Products have been characterized by X-ray diffraction and solid-state (27)Al MAS and MQMAS NMR.

Electrolytic synthesis of aqueous aluminum nanoclusters and in situ characterization by femtosecond Raman spectroscopy and computations

“…Although the flat cluster [Al 13 (μ 3 -OH) 6 (μ 2 -OH) 18 (H 2 O) 24 ] 15+ is commonly considered a minor component in Al speciation that does not appear in published predominance (i.e., Pourbaix) diagrams (28,29), it can now be synthesized in large quantities (30)(31)(32). Here, we demonstrate complete atom economy and step economy in the selective synthesis of the Al 13 cluster using…”

“…This cluster contains only distorted octahedral AlO 6 groups, lacking the tetrahedral AlO 4 core of the Keggin cluster. The ease of isolating the flat cluster points to the efficacy of the electrolysis method for selective synthesis through precision pH control (32). The electrolysis method is also especially well suited for in situ analysis because of the lack of any additional reagents.…”

Heat capacities and thermodynamics of formation of flat-Al13 nitrate – [Al13(OH)24(H2O)24](NO3)15·11H2O

“…The flat-Al 13 nitrate sample was synthesized according to the published methods of Wang et al [8]. Briefly, Al(NO 3 ) 3 Á9H 2 O was dissolved in Millipore water (q = 18.2 MX) and zinc metal powder was added to the clear solution.…”

“…The second main class contains clusters consisting solely of distorted octahedrally coordinated aluminum ions and hydroxyl linkages arranged analogously to those in a hexagonally close-packed layered hydroxide structure such as brucite [4]. These species increase in nuclearity and charge in a ring-like manner from [Al 8 (l 3 -OH) 3 (l 2 -OH) 12 (H 2 O) 18 ] 10+ (aq) [5] to [Al 13 (l 3 -OH) 6 (l-OH) 18 (H 2 O) 24 ] 15+ (aq) [6][7][8][9][10] (figure 1) and are termed ''flat'' structures, reflecting their more sheet-like topology compared to the Keggin Al 13 ions. These clusters have proven to be useful experimental models for understanding aqueous exchange reactions at the atomic level, as they expose similar (aluminum + oxygen) coordination chemistries found in soil minerals [11].…”

“…These clusters have proven to be useful experimental models for understanding aqueous exchange reactions at the atomic level, as they expose similar (aluminum + oxygen) coordination chemistries found in soil minerals [11]. Until recently the [Al 13 (l 3 -OH) 6 (l-OH) 18 (H 2 O) 24 ] 15+ (aq) (flat-Al 13 ) polynuclear aluminum hydroxide ions could not be synthesized in high yield or with fast reaction times [7,8,10]; thus they have often been omitted from speciation studies and relatively few reports are currently available on them, e.g. [4,[12][13][14].…”