I understand that ate complexes can result from the addition of carbanions to neutral aluminum alkyls.

I was wondering what the balanced equation for this reaction is/what the structure would be in solid state - like does it dimerize?

$$\ce{2 LiCH2CH3 + Al2(CH2CH3)6 -> ?}$$


The crystal structure of lithium tetraethylaluminate has been published (DOI) and as far as I can tell from the abstract, there is no indication for a dimeric anion here. It might be save to assume that the balanced equation therefore can be written as:

$\ce{2 LiCH2CH3 + Al2(CH2CH3)6 -> 2 Al(CH2CH3)4^{\delta-}\,Li^{\delta+}}$

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    $\begingroup$ That is correct, but in solid state it forms chains of alternating Lithium and Aluminium, both in tetraedral coordination. (Separated by 7Å, hold together by van-der-Waals-Forces.) However, the paper refers to the compound as $\ce{LiAl(CH2CH3)4}$, but also suggest ionic character. They assume some electron density of $\ce{Al\bond{-}C}$ is shifted towards the Lithium forming a more centre bond with some covalent character. (I am just adding that because the question points to the sold state structure.) $\endgroup$ – Martin - マーチン Apr 16 '14 at 5:56
  • $\begingroup$ @Martin The -/+ added for clarity (and as separators) might indeed lead to wrong conclusions. I'll fix that. $\endgroup$ – Klaus-Dieter Warzecha Apr 16 '14 at 6:02

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