Carbon‐Atom Extrusion from Halobenzenes and Its Coupling with a Methylene Ligand to Form Acetylene

Mechanistic aspects of an unusual gas‐phase reaction of [LaCH₂]⁺ with halobenzenes have been investigated using Fourier‐transform ion cyclotron resonance (FTICR) mass spectrometry combined with density functional theory (DFT) calculations. In this thermal process a carbon‐atom from the benzene ring, most likely the ipso‐position, and the carbene ligand are coupled to form C₂H₂.