CH ₅ ⁺ : The Cheshire Cat Smiles

Sometimes, even seemingly simple molecules can be extremely hard to characterize. One such molecule, protonated methane (CH), has resisted structural characterization by molecular spectroscopy since its discovery by mass spectrometry in the 1950s. CHis implicated as a reactive intermediate in hydrocarbon reactions and may play a role in astrochemical reactions, but its highly fluxional character and special bonding have complicated characterization. Marx and Parrinello describe the theoretical and experimental efforts to capture this elusive molecule's properties that have led to the successful acquisition of a high-resolution infrared spectrum of free CHby White et al . (page [135][1]). [1]: http://www.sciencemag.org/cgi/content/short/284/5411/135