Evidence for near-neighbour interactions in some substituted methyl derivatives of transition metals including the molecular crystal structure determinations of (π-C5H5)Fe(CO)2CH2·CO2H and (π-C5H5)Mo(CO)3CH2·CO2H

Abstract

The preparation and properties of the acids, M–CH₂·CO₂H, and amides, M–CH₂·CONH₂ are described, where M =π-C₅H₅Fe(CO)₂, π-C₅H₅Mo(or W)(CO)₃, Mn(or Re)(CO)₅, or (DMG)₂Co py (DMG = dimethylglyoximate). pK_a Determinations show that the acids are very weak. The crystal structures of the iron and molybdenum acids have been determined; unusual distances are found in the former. It is suggested that there is direct interaction between the metal and β-substituents in these complexes. By calculations, the possible extent of overlap between an iron atom and either a β-carbon atom or a hydrogen atom attached to a β-carbon is estimated.