Iron Methyl and Neosilyl Complexes with Neutral N-Donor Ligands in Cross Coupling Reactions

High Resolution Image Download MS PowerPoint Slide Low-temperature treatment of ferric chloride with organolithium compounds in the presence of chelating N-donor ligands gave an array of new ferrous alkyl complexes. TMEDA ( N, N, N ′, N ′-tetramethylethylenediamine) stabilizes the mixed alkyl/chlorido complexes (TMEDA)FeCl(CH 3 ) and (TMEDA)FeCl(CH 2 SiMe 3 ), as well as the dineosilyl complex (TMEDA)Fe(CH 2 SiMe 3 ) 2 . Efforts to synthesize the dimethyl species led to the formation of higher alkylated iron lithium ate complexes including the long sought after [Li 2 Fe(CH 3 ) 4 ] entity. Switching to sterically slightly more demanding TEEDA ( N, N, N ′, N ′-tetraethylethylenediamine) gave access to elusive (TEEDA)Fe(CH 3 ) 2 and complexes analogous to the ones obtained with TMEDA. The paramagnetic complexes were characterized using 1 H/ 7 Li NMR and FTIR spectroscopy, as well as single crystal X-ray diffraction. Investigations toward their C(sp 2 )–C(sp 3 ) cross-coupling reactivity and comparison to their respective in situ generated mixtures revealed an unprecedented dependence of the product Z – E isomerism on the employed reactant ratio.