Heterometallic aluminates: alkali metals trapped by an aluminium aryloxide claw

Abstract

A series of heterometallic aluminium-alkali metal species [AlMMe2{2,6-(MeO)2C6H3O}2]n have been isolated for lithium, sodium and potassium. These compounds can be generated by the reaction of [AlMe2{2,6-(MeO)2C6H3O}]2 with the metallated phenol [M{2,6-(MeO)2C6H3O}]n or through the reaction of the mixture of AlMe3 and the appropriate alkali metal alkyl base with two equivalents of 2,6-dimethoxyphenol. In the heterometallic species obtained, the {AlMe2{2,6-(MeO)2C6H3O}2}(-) moiety is observed and could be described as a claw which fixes the alkali ion by the phenoxide oxygen atoms while the methoxy groups help to stabilize their coordination sphere. All compounds have been characterized by NMR spectroscopy and X-ray diffraction methods. Catalytic studies reveal that these compounds are active in ring-opening polymerization of L-lactide.

Aluminum Alkali Metalate Derivatives: Factors Driving the Final Nuclearity in the Crystal Form

“…They were characterized in solution by multinuclear NMR spectroscopy and in the solid state by X‐ray single crystal diffraction. We have previously described the synthesis of these species but we could not isolate them as single crystals . In this work, we have obtained the sodium derivative as a crystalline material, [Na{2,6‐(MeO) 2 C 6 H 3 O}] 6 ( Na2H6S ), which allowed us to determine its structure by X‐ray single crystal diffraction study (see below).…”

“…All reagents were commercially obtained and used without further purification. Benzylsodium and [K{2,6‐(MeO) 2 C 6 H 3 }] n ( K2H6S ) were prepared as reported.…”

“…In this context, our work is focused on the study of heterometallic ‐ate species containing aluminum and alkali metals with well‐defined structures . We are interested in preparing aluminates with functionalized aryloxide groups as bridging ligands.…”

“…In our previous work, we isolated new heterometallic ‐ate species of different stoichiometry and nuclearity: [AlLiMe 3 {2,6‐(MeO) 2 C 6 H 3 O}] 3 ( AlLi1H , where 1H accounts for a single hexagon) and [AlLiMe 2 {2,6‐(MeO) 2 C 6 H 3 O} 2 ] 2 ( AlLi3S , where 3S accounts for three squares) from the reaction of the hexametallic lithium aryloxide cage [Li{2,6‐(MeO) 2 C 6 H 3 O}] 6 ( Li2H6S where 2H and 6S account for two hexagons and six squares, respectively) with two different aluminum precursors, [AlMe 3 ] 2 and [Al{2,6‐(MeO) 2 C 6 H 3 O}Me 2 ] 2 {[Al(OR)Me 2 ]} (Scheme ) . Then, we extended the study to sodium and potassium aryloxides [M{2,6‐(MeO) 2 C 6 H 3 O}] 6 ( M2H6S ) by using [Al(OR)Me 2 ] as the aluminum precursor, which led to the isolation of the species [AlMMe 2 {2,6‐(MeO) 2 C 6 H 3 O} 2 ] n ( AlNa3S and AlK3S for M = Na and K) with central Al 2 M 2 cores analogous to the lithium one …”

Aluminates with Fluorinated Schiff Bases: Influence of the Alkali Metal–Fluorine Interactions in Structure Stabilization

“…Ligands with O- and N- donor groups are also scarce in these compounds. In our group, we described aluminate derivatives with functionalized phenolates as bridging ligands bearing donor substituents in ortho positions [36,37,38], and more recently, with terpene oximate ligands with O- and N- donor atoms [39].…”