Considering the assumed flexibility of the ferrocene moiety, we anticipated the amide protons in AS4 next to the ferrocene moiety, N(3)-H and N(4)-H, to show greater shielding effects in CDCl3 as compared to DMSO-d6, consistently with a preference for the cis conformation. In contrast, in DMSO-d6, the intercalation of polar solvent molecules is likely to disrupt the ferrocene conformation, favouring an expanded trans conformation of the substituent chains (Figure ). An initial analysis of the 1 H-NMR spectra was obtained on samples in deuterated CDCl3 and DMSO-d6. The gradual addition of DMSO-d6 typically leads to significant changes in the chemical shift of free or weakly hydrogen-bonded NH protons, while strong intramolecularly hydrogen-bonded NH groups tend to show little or no effect switching to DMSO-d6. ) observed in vt-NMR experiment of AS4 in CDCl3 (c = 1.24 mM) from 298 to 328 K.