15N, 14N, 13C and 1H NMR study of mesoionic methylides and thiocarbonyl ylides with a 2,3- diphenyltetrazolium ring

Abstract

15N, 14N, 13C and 1H NMR data were collected for the identification and structure determination of several mesoionic 2,3-diphenyltetrazolium methylides ( 1) and mesoionic thiocarbonyl ylides ( 2) with a 2,3-diphenyltetrazolium ring. In solution, mesoionic thiocarbonyl ylides can exist as either a cyclic form or a mesoionic cyclic form ( 2) depending on the solvent and on the exocyclic group, whereas the mesoionic 2,3-diphenyltetrazolium methylides exist rather as a cyclic mesoionic form ( 1). The NMR data indicate that the 2,3-diphenyltetrazolium methylides and the mesoionic thiocarbonyl ylides in CF 3 COOH solution are protonated at the exocyclic group.