A full conformational analysis of six 1,2,4-monosubstituted carbanion 1,2,4-triazolium ylides 4 a-f was performed using AM1, PM3 and HF/3-21G methods. The C-type conformers were found as the most stable structures by these different methods. This study also includes a qualitative estimation of the chemical behavior of triazolium ylides 4 a-f as nucleophilic agents on the level of ylide carbon atoms. The ab initio 3-21G method seems to be the most suitable in the characterization of these molecular systems.