How unstable can it be? Gas-phase measurements on the 3-cyclobutenyl cation were combined in a thermodynamic cycle to provide the first experimental determination of the heat of formation of cyclobutadiene (see scheme, IP = ionization potential, BDE = bond-dissociation energy). The resulting value of 428 ± 16 kJ mol-1 is in good accord with previous predictions based upon similar energetic determinations of benzo- and phenylcyclobutadiene. (Figure Presented).
- Ab initio
- Mass spectrometry