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The aluminyl compounds [M{Al(NONDipp)}]2(NONDipp= [O(SiMe2NDipp)2]2–, Dipp = 2,6-iPr2C6H3), which exist as contacted dimeric pairs in both the solution and solid states, have been converted to monomeric ion pairs and separated ion pairs for each of the group 1 metals, M= Li, Na, and K. The monomeric ion pairs contain discrete, highly polarized Al–Mbonds between the aluminum and the group 1 metal and have been isolated with monodentate (THF, M= Li and Na) or bidentate (TMEDA, M= Li, Na, and K) ligands at M. The separated ion pairs comprise group 1 cations that are encapsulated by polydentate ligands, rendering the aluminyl anion, [Al(NONDipp)]−“naked”. For M= Li, this structure type was isolated as the [Li(TMEDA)2]+salt directly from a solution of the corresponding contacted dimeric pair in neat TMEDA, while the polydentate [2.2.2]cryptand ligand was used to generate the separated ion pairs for the heavier group 1 metals M= Na and K. This work shows that starting from the corresponding contacted dimeric pairs, the extent of the Al–Minteraction in these aluminyl systems can be readily controlled with appropriate chelating reagents.

We report the oxidative addition of phenylsilane to the complete series of alkali metal (AM) aluminyls [AM{Al(NONDipp)}]2(AM= Li, Na, K, Rb, and Cs). Crystalline products (1-AM) have been isolated as ether or THF adducts, [AM(L)n][Al(NONDipp)(H)(SiH2Ph)] (AM= Li, Na, K, Rb, L = Et2O, n= 1; AM= Cs, L = THF, n= 2). Further to this series, the novel rubidium rubidiate, [{Rb(THF)4}2(Rb{Al(NONDipp)(H)(SiH2Ph)}2)]+[Rb{Al(NONDipp)(H)(SiH2Ph)}2]−, was isolated during an attempted recrystallization of Rb[Al(NONDipp)(H)(SiH2Ph)] from a hexane/THF mixture. Structural and spectroscopic characterizations of the series 1-AMconfirm the presence of μ-hydrides that bridge the aluminum and alkali metals (AM), with multiple stabilizing AM···π(arene) interactions to either the Dipp- or Ph-substituents. These products form a complete series of soluble, alkali metal (hydrido) aluminates that present a platform for further reactivity studies.