Alkyl Abstraction from a Trialkylyttrium Complex [YR₃(thf)₂] (R = CH₂SiMe₃) Using a Group‐13 Element Lewis Acid ER₃ (E = B, Al, Ga, In) – Structural Characterisation of the Ion Pair [YR₂(thf)₄]⁺[GaR₄]^– and of ER₃ (E = B, Al, Ga)

Abstract

Abstract The alkyl abstraction reaction of [YR 3 (thf) 2 ] (R = CH 2 SiMe 3 ) with group‐13 trialkyl complexes [(ER 3 ) n ] (E = B, Ga, In: n = 1; E = Al: n = 2) forming cationic yttrium species [YR 2 (thf) 4 ] + [ER 4 ] – (E = Al, Ga, In) shows a strong dependence on the Lewis acidic metal centre E and on the solvent basicity. Whilst the boron compound does not react with [YR 3 (thf) 2 ], the heavier homologues form the ion pairs [YR 2 (thf) 4 ] + [ER 4 ] – (E = Al, Ga, In) which dissociate to give the neutral compounds in apolar solvents such as benzene. Single‐crystal structure analysis of the gallate [YR 2 (thf) 4 ] + [GaR 4 ] – shows the presence of an ion pair with cis ‐arranged alkyl ligands in the octahedral yttrium cation and a tetrahedral gallate anion. Group‐13 trialkyl compounds [(ER 3 ) n ] (E = B, Al, Ga), all liquids at room temperature, and [Li(12‐crown‐4) 2 ] + [AlR 4 ] – were characterised by single‐crystal X‐ray diffraction and NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)