A novel route to metallacyclopropene (η2-vinyl) complexes from alkynes: synthesis and X-ray crystal structure of trans-[ReCl{C(CH2Ph)CH2}(Ph2PCH2CH2PPh2)2][BF4]

Abstract

Treatment of the allene complex trans-[[graphic omitted]CHPh)(dppe)₂](dppe = Ph₂PCH₂CH₂PPh₂) with acids, HA (A = BF₄ or PF₆), in CH₂Cl₂ or tetrahydrofuran gives the metallacyclopropene (η²-vinyl) complex trans-[[graphic omitted]H₂}(dppe)₂][A] whose structure (A = BF₄) has been authenticated by X-ray crystallography; the site of protonation is in agreement with extended Hückel calculations which show, in the HOMO, a high electronic density on the allene carbon atom which is not directly bonded to the metal.