Preparation, reactions, and spectroscopic investigation of the 1,1,3,3-tetramethylimidazolidinium and 1,1,4,4-tetramethylpiperazonium dications

Abstract

The title dications are prepared in a single step by the reaction of N,N,N′,N′-tetramethyl-1,2-diaminoethane (tmen) with the halogenoalkanes CH2X2 (X = Cl, Br, or I)orCH2XCH2X (X = Cl or Br), respectively. These bulky dications are useful for the precipitation of complex ions from solution, and show selectivity for doubly-charged anions. Tmen also reacts with CBr4 to yield a dibromo-imidazolidinium heterocyclic dication, whereas reaction with CHBr2CHBr2 produces the dihydrobromide of tmen. Vibrational and nmr spectra are reported, and the protons of the CH2 group between the two quaternary nitrogen atoms of the tetramethylimidazolidinium dication are shown from the nmr data to possess acidic character.