Testing the Validity of the Conventional Resonance Model for Protonated Carbonyl, Imine and Thiocarbonyl Compounds. An Ab Initio Valence Bond Study
2008-05-15T00:00:00Z (GMT) by
The conventional resonance model describes protonated carbonyls, imines, and thiocarbonyls by a superposition of two structures, one π polar-covalent and the other of carbenium type. The validity of this model is clearly supported by high level valence bond calculations, giving a 32% weight for the carbenium form in protonated carbonyl, 19% in protonated formamine and thioformaldehyde. The carbenium form is further stabilized by π-donating substituents. Solvation effects do not fundamentally change the gas-phase picture.