N-Heterocyclic carbene, carbodiphosphorane and diphosphine adducts of beryllium dihalides: synthesis, characterisation and reduction studies

Abstract

Reaction of several N-heterocyclic carbenes, a carbodiphosphorane, and bis(diphenylphosphino)ethane (DPPE) with [BeX₂(OEt₂)₂] (X = Br or I) have yielded a variety of beryllium dihalide adduct complexes, all of which were crystallographically characterised. Attempts to reduce the compounds to low oxidation state beryllium complexes using a variety of reducing agents have been carried out, but were of limited success. However, reaction of [(IPr)BeBr₂] (IPr = :C{(DipNCH)₂}; Dip = 2,6-diisopropylphenyl) with the aluminium(I) heterocycle, [:Al(^DipNacnac)] (^DipNacnac = [HC(MeCNDip)₂]⁻) afforded the adduct complex, [{(IPr)(Br)Be(μ-H)}₂], while reduction of [(IPr)BeBr₂] with potassium naphthalenide gave the beryllium naphthalenediyl complex, [(IPr)Be(C₁₀H₈)]. Furthermore, reaction of [{(DPPE)BeI₂}_∞], with [:Al(^DipNacnac)] led to insertion of the Al centre of the heterocycle into a Be–I bond, and formation of a rare example of an Al–Be bonded complex, [(DPPE)(I)Be–Al(I)(^DipNacnac)].