Structure and properties of protonated N-alkyl-2-aza[3]ferrocenophanes

Protonation of N-alkyl-2-aza[3]ferrocenophanes by HCl and NH4PF6 affords hexafluorophosphate salts having a trialkylammonium group. Structures of the protonated and unprotonated N-(p-methylbezyl)-2-aza[3]ferrocenophanes were determined by X-ray crystallography. Variable temperature 13C{1H} NMR spectra of the N-protonated N-hexyl-2-aza[3]ferrocenophane revealed inversion of the nitrogen of the 2-aza[3]ferrocenophane on the NMR time scale probably via partial deprotonation of the nitrogen atom. Cyclic voltammograms of the N-protonated compounds exhibited reversible redox peaks at higher potentials than those of the corresponding neutral ferrocenophanes.