Synthesis and molecular structure of hexakis(tetrahydrofuran)calcium bis[trimethyl-(diphenylamino)alanate]

The reaction of AlMe3 with (dme)(2)Ca(NPh2)(2) in a solvent mixture of toluene and THF yields the addition product [(thf)(6)Ca] [Me3Al-NPh2](2) (1). In solution the anion of this solvent-separated complex 1 [delta(Al-27) = 153] partly dismutates into ([AlMe2(NPh2)(2)](-) [delta(Al-27) = 179] and [AlMe4](-) [delta(Al-27) = 155]. The [Me3Al-NPh2] anion shows a strong backdonation of negative charge from the nitrogen atom into one phenyl ring whereas the other phenyl group forms hyperconjugative bonds between the p-orbital of the ipso-carbon atom and the sigma(*) (Al-C) orbital leading to a slight elongation of one of the Al-C bonds. (c) 2008 Elsevier B.V. All rights reserved.