Allenylidene and derived alkynyl complexes of iron(II) with the {FeBr(Et2PCH2CH2PEt2) 2}+ centre

Article abstract of DOI:10.1016/S0022-328X(03)00766-6

The allenylidene complexes trans-[FeBr{=C=C=C(R)Ph}(depe)₂] [BPh₄] (depe=Et₂PCH₂CH₂ PEt₂; R=Me 1, Ph 2) were obtained by treatment of a methanolic solution of trans-[FeBr₂(depe)₂] with the appropriate alkynol HC≡C-C(R)Ph(OH), in the presence of Na[BPh₄]. The methylallenylidene ligand in 1 undergoes reversible deprotonation (by NaOMe) to yield the enynyl (or ene-yne) complex of iron(II), trans-[FeBr{-C≡C-C(= CH₂)Ph}(depe)₂] 3. The diphenylallenylidene ligand in 2 undergoes regioselective hydride γ-addition on reaction with K[B{CH(Me)Et}₃H] to afford the alkynyl complex trans-[FeBr {-C≡C-C(H)Ph₂}(depe)₂] 4.