title: Dimeric aluminum-phosphorus compounds as masked frustrated Lewis pairs for small molecule activation.
abstract: Hydroalumination of aryldialkynylphosphines RP(C≡C-(t)Bu)(2) (R = Ph, Mes) with equimolar quantities of diethylaluminum hydride afforded mixed alkenyl-alkynyl cyclic dimers in which the dative aluminum-phosphorus bonds are geminal to the exocyclic alkenyl groups. Addition of triethylaluminum to isolated 1 (R = Ph) or to the in situ generated species (R = Mes) caused diethylaluminum ethynide elimination to yield the arylethylphosphorus dimers 2 and 3. These possess a chair-like Al(2)C(2)P(2) heterocycle with intermolecular Al-P interactions. The boat conformation (4) was obtained by the reaction of (t)Bu-P(C≡C-(t)Bu)(2) with di(tert-butyl)aluminum hydride. Despite being dimeric, 2 behaves as a frustrated Lewis pair and activates small molecules. The reaction with carbon dioxide gave cis/trans isomeric AlPC(2)O heterocycles that differ only by the configuration of the exocyclic alkenyl unit. Four isomers resulted from the reaction with phenyl isocyanate. This is caused by cis/trans isomerization of the initial C=O adduct and subsequent rearrangement to the AlPC(2)N heterocycle, being the C=N adduct.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Universität Münster, D-48149 Münster, Germany.
authors.forename: Steffi
authors.initials: S
authors.lastname: Roters
authors.forename: Christian
authors.initials: C
authors.lastname: Appelt
authors.forename: Hauke
authors.initials: H
authors.lastname: Westenberg
authors.forename: Alexander
authors.initials: A
authors.lastname: Hepp
authors.forename: J Chris
authors.initials: JC
authors.lastname: Slootweg
authors.forename: Koop
authors.initials: K
authors.lastname: Lammertsma
authors.forename: Werner
authors.initials: W
authors.lastname: Uhl