Reactions of Laser-Ablated Iron Atoms with Halomethanes: Infrared Spectra, Density Functional Calculations, and Structures of Simple Iron Insertion and Methylidene Complexes

Abstract

Reactions of laser-ablated Fe atoms with halomethanes and ethane have been investigated through matrix infrared spectra and density functional calculations. Only insertion complexes are identified from reactions of Fe with methyl fluoride and ethane, parallel to the previously observed insertion complex CH3−FeH from the photochemical reaction with methane. However, Fe also forms methylidene complexes through α-X migration in the insertion products from Fe reactions with di-, tri-, and tetrahalomethanes. Calculated structures show no agostic distortion in these methylidene complexes. However, an interesting distortion and elongation of the C−Cl bond is observed in the Fe insertion products, such as H2ClC−FeCl, while no such distortion of the C−H or C−F bond is found in analogous calculated structures for H2FC−FeCl. This distortion is likely due to a Cl lone pair to Fe bonding interaction that ultimately leads to formation of the lower energy CH2═FeCl2 methylidene complex. This Cl atom transfer is reversibl...