Reactions of [Fe2(η-dienyl)2(CO)4–n(CNR)n] complexes (dienyl = C5H5, C5H4Me, or C9H7; R = alkyl or benzyl; n= 1 or 2) with alkyl halides and other alkylating agents. The crystal structure of cis-[Fe2(η-C5H4Me)2(CO)3{C(NMe2)µ}]I

Abstract

The title complexes react with alkyl halides, R′X, to give the salts [Fe₂(η-dienyl)₂(CO_t)(CO_µ)(L_t){CN(R′)R_µ}][X](L = CO or CNR). The ease of the reaction is affected by the nature of the dienyl ligand, n, R, R′, and X so that no reaction occurs when R or R′= Bu^t or X = Cl, and it is much slower when R or R′ are secondary alkyl groups. Other alkylating agents may be used but give much less satisfactory results. The i.r. and ¹H and ¹³C n.m.r. spectra of the salts suggest that isomerism occurs, but its nature is not clear. The structure of cis-[Fe₂(η-C₅H₄Me)₂-(CO_t)₂(CO_µ){C(NMe₂)_µ}]I has been determined by an X-ray diffraction study. It has been solved using the heavy-atom method from photographic data and refined by full-matrix least squares to R= 0.078 for 724 non-zero unique reflections. Crystals of this compound are orthorhombic with space group Pmn2, Z= 2, a= 13.87(2), b= 9.03(1), and c= 8.05(1)Å.