N-Heterocyclic carbene-induced transmethylation in tungsten imido alkylidene bistriflates: unexpected formation of an N-heterocyclic olefin complex

Abstract

The reaction of [W(N-2,6-ⁱPr₂C₆H₃)(CHCMe₂Ph)(OTf)₂(DME)] (DME = 1,2-dimethoxyethane, OTf = CF₃SO₃) with the N-heterocyclic carbene (NHC) 1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene (IMesH₂) leads to DME activation followed by transmethylation and in due consequence to the formation of the N-heterocyclic olefin complex [W(N-2,6-ⁱPr₂C₆H₃)(CHCMe₂Ph)(OTf)₂(IMesH₂CH₂)] along with [W(N-2,6-ⁱPr₂C₆H₃)(CHCMe₂Ph)(OTf)(IMesH₂)(κ²-O(CH₂)₂OMe)], [1,3-bis(2,4,6-trimethylphenyl)-2-methylimidazolidinium⁺ (OTf⁻)] and [1,3-bis(2,4,6-trimethylphenyl)-2-H-imidazolidinium⁺ (OTf⁻)]. A reaction pathway is proposed and confirmed by the use of ¹³C-labelled compounds; structures of the products were verified by NMR and/or single-crystal X-ray analysis.