Through-bond interaction in the radical cation of N,N-dimethylpiperazine: Resonance Raman spectroscopy and quantum chemical calculations

The radical cation of N,N-dimethylpiperazine is investigated by resonance Raman spectroscopy and ab initio calculations. The calculations strongly support the assignment of the vibrational spectrum to a chair conformation. It is shown that a dramatic geometry relaxation following ionization allows a much more efficient interaction between the nitrogen 'lone pairs' than in the neutral ground state.