title: Testing the validity of the conventional resonance model for protonated carbonyl, imine and thiocarbonyl compounds. An Ab initio valence bond study.
abstract: The conventional resonance model describes protonated carbonyls, imines, and thiocarbonyls by a superposition of two structures, one pi 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 pi-donating substituents. Solvation effects do not fundamentally change the gas-phase picture.
authors.affiliation: UPMC Université Paris 06, UMR 7616, Laboratoire de Chimie Théorique, Case courrier 137, 4 place Jussieu, 75252 Paris, France. braida@lct.jussieu.fr
authors.forename: Benoît
authors.initials: B
authors.lastname: Braïda
authors.forename: Dilshaad
authors.initials: D
authors.lastname: Bundhoo
authors.forename: Bernd
authors.initials: B
authors.lastname: Engels
authors.forename: Philippe C
authors.initials: PC
authors.lastname: Hiberty
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008956:Models, Chemical; D011522:Protons; D011789:Quantum Theory; D015203:Reproducibility of Results; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D007097:Imines; D011522:Protons; D013438:Sulfhydryl Compounds