Quaternary 4-Amino-1,2,4-triazolium Salts: Crystal Structures of Ionic Liquids and N-Heterocyclic Carbene (NHC) Complexes

Quaternary salts were prepared by reaction of 4-amino-1,2,4-triazole and 4-amino-3,5-dialkyl- 1,2,4-triazoles (alkyl = Me, Et) with dimethyl and diethyl sulfate at ambient temperature. Subsequent ion metathesis gave hexafluorophosphates and bis(trifluoromethylsulfonyl)imides as crystalline derivatives or ionic liquids.Methylation at 100 C gave the 4-(dimethylamino)-1-methyl-1,2,4- triazolium salt, a precursor for a new carbene ligand which was incorporated into Ag and Rh complexes. The synthesis of 5-bromo-4-(dimethylamino)-1-methyl-1,2,4-triazolium hexafluorophosphate is also reported. Crystal structures of fourteen compounds have been determined by X-ray diffraction