A Persistent Alkylaluminum Peroxide: Surprising Stability of a Molecule with Strong Reducing and Oxidizing Functions in Close Proximity

Abstract

The reaction of the beta-diketiminato coordinated aluminum dihydride, [{HC[C(Me)N-C(6)H(5)](2)}AlH(2)] (1) with bis(trimethylsilyl)methyllithium afforded the monoalkylaluminum derivative [{HC[C(Me)N-C(6)H(5)](2)}Al(H)-CH(SiMe(3))(2)] (2) by the precipitation of lithium hydride. Interestingly, treatment of 2 with tert-butyl hydrogenperoxide did not result in the formation of the simple oxidation product containing a hydroxo or alkoxo group, instead, elemental hydrogen was released and the hydrido ligand attached to aluminum was replaced by an intact tert- butylperoxo group. The Al-C bond, which normally is extremely sensitive towards an attack of oxygen, was not affected. Hence, the product exhibits quite conflicting chemical properties in a close proximity: a strongly reducing Al-C bond beside an oxidizing peroxo group.

Synthesis, characterization and reactivity of an imidazolin-2-iminato aluminium dihydride

“…This is in good agreement with the respective values in (Dipp)nacnacAl(BH 4 ) 2 for which an η 2 coordination mode of the BH 4 moieties to the aluminium atom has also been described. 46 11 B NMR spectra indicated the conversion to be complete. Accordingly, the reaction on a preparative scale in toluene granted the analytically pure aluminium dibromide {μ-LAlBr 2 } 2 (5) in 57% yield (Scheme 2).…”

“…The β-diketimino group, in particular, has been a key ligand to a rich chemistry of respective aluminium dihydrides. [9][10][11][12] A prominent example is II (Fig. 1), which can The guanidinate IV, the phosphinimide V, as well as the troponimide VI (Dipp = 2,6-diisopropylphenyl).…”

Reactions of β-diketiminatoaluminum hydrides with tert-butyl hydrogenperoxide – Facile formation of dialuminoxanes containing Al–O–Al groups

“…One compound possessed Ga 3 (O 2 ) 3 heterocycles (Scheme 1) in which three gallium atoms were bridged by three peroxo groups [6,7]. Furthermore, we were able to isolate even an organoaluminum peroxide (Scheme 1) which had a tert-butylperoxo ligand beside a strongly reducing and generally very oxygen sensitive Al-C bond [8]. All compounds had CH(SiMe 3 ) 2 groups attached to their aluminum or gallium atoms.…”

“…Furthermore, they may show unique coordination behaviour similar to transition metal compounds. In recent investigations we found an easy access to those peroxides by the treatment of the corresponding organoelement hydrides with different hydrogenperoxides and by the release of elemental hydrogen [6][7][8]. One compound possessed Ga 3 (O 2 ) 3 heterocycles (Scheme 1) in which three gallium atoms were bridged by three peroxo groups [6,7].…”

Persistent Alkylgallium Peroxides – Synthesis of the Cage Compound Na4[(Ga‐R)3(O2)3(O)]2(Et2O)(DABCO) [R = CH(SiMe3)2]

“…[5] Recently the crystal structures of two relatively inert alkylaluminum and -gallium peroxides were reported, which were stabilized by bis(trimethylsilyl)methyl groups. [6,7] Both compounds were obtained by the simple reactions of alkylelement hydrides with hydrogen peroxide or tert-butyl hydrogen peroxide and the release of hydrogen.…”