Pyrazine diradicals, carbenes, ylides, and distonic ions probed by theory and experiment22Dedicated to Professor M.T. Bowers on the occasion of his 60th birthday.

The [C4,H4,N2] potential energy hypersurface relating to pyrazine and its hydrogen shift isomers has been investigated computationally using hybrid Hartree–Fock/density functional theory and through a variety of tandem mass spectrometry experiments (metastable ion, collision-induced dissociation, and neutralization reionization mass spectrometry). In addition to the conventional pyrazine structure 1, its α-ylide 2, β-ylide 3, and the …