Electronic properties of the trimethylenemethaneiron tricarbonyl group

The substituent electronic effects of trimethylenemethaneiron tricarbonyl [TMMFe(CO)3] have been studied, with σ values reported. Determination of these values was accomplished through three different techniques: a study of acidity relative to benzoic acid with TMMFe(CO)3 acting as a substituent of benzoic acid; 19F-nuclear magnetic resonance (NMR) shielding analysis of m-fluorophenylTMMFe(CO)3; and 13C-NMR shielding analysis of phenylTMMFe(CO)3. The TMMFe(CO)3 group behaves in much the same manner as a phenyl group (i.e. weakly electron releasing by resonance and weakly electron attracting by induction). The syntheses of the substituted phenyltrimethyleneiron tricarbonyl compounds are described.