The Methylene-bridged Dialuminium Compound R 2 Al-CH 2 -AlR 2 [R=CH(SiMe 3 ) 2 ] as an Effective Chelating Lewis Acid – Adducts with Halides, Perchlorate and Isopropylamide

The new methylene-bridged dialuminium compound Aryl 2 Al-CH 2 -AlAryl 2 1b was synthesised from Cl 2 Al-CH 2 -AlCl 2 and four equivalents of LiAryl [Aryl=C 6 H 2 (2,4,6-i-Pr) 3 ]. A 1 : 2 stoichiometric ratio of the starting compounds afforded the dimeric aluminium halide (Aryl 2 AlCl) 2 (2) by dismutation. The coordination behaviour of the related, but more easily available dialuminium compound R 2 Al-CH 2 -AlR 2 [R=CH(SiMe 3 ) 2 ] 1a was explored. It yields the Lewis acid base adducts [M][R 2 Al-CH 2 -AlR 2 (μ-X)] [3a, M=Li(TMEN) 2 , X=Cl; 3b, M=Li(TMEN) 2 , X=Br; 3c, M=K(18-crown-6), X=ClO 4 ; 3d, M=Li(TMEN) 2 , X=NH(i-Pr)] with X residing in a bridging position between the two Al atoms as evident from NMR spectroscopy and X-ray crystallography (3b, 3c, 3d). Compound 3c is a unique example of a stable, in organic solvents soluble adduct that features a ClO 4 - anion coordinated by an alkylaluminium compound via two of its oxygen atoms. The Methylene-bridged Dialuminium Compound R 2 Al-CH 2 -AlR 2 [R=CH(SiMe 3 ) 2 ] as an Effective Chelating Lewis Acid – Adducts with Halides, Perchlorate and Isopropylamide