Michigan Publishing, Arkivoc, 3(2012), p. 20-37, 2011
DOI: 10.3998/ark.5550190.0013.303
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Pyrazolium-3-sulfonates and pyrazolium-4-sulfonates possessing the iminiomethanesulfonate and the 3-iminio-pro-1-ene-2-sulfonate partial structure are prepared. Formally, they represent sulfur analogs of cross-conjugated (CCMB) and pseudo-cross-conjugated heterocyclic mesomeric betaines (PCCMB) and sulfur trioxide adducts of abnormal N-heterocyclic carbenes (aNHC) and N-heterocyclic carbenes (NHC), respectively. The theoretical as well as experimental vibrational spectra of these two classes are compared. Results of calculations of HOMO/LUMO profiles and an X-ray single crystal structure analysis are presented.