Dissociation chemistry of the hydrogen-bridged radical cation [CH2O ⋯ H ⋯ OC–OCH3]·+: proton transport catalysis and charge transfer11Dedicated to the memory of Professor Robert R. Squires.

Tandem mass spectrometry based experiments on the decarbonylation products of ionized methyl-β-hydroxypyruvate (MHP) and dimethyloxalate (DMO) show that the hydrogen-bridged radical cation (HBRC) CH2O ⋯ H ⋯ OC–OCH3·+ is a stable species in the gas phase. Its low energy dissociation products are protonated methylformate, HOC(H)OCH3+, and the formyl radical, HCO·. The HBRC isomers HOCH2C(O)OCH3·+ (ionized methylglycolate) and (CH3O)2CO·+ …