The high solubility of 2 in various apolar solvents precluded us from obtaining crystals suitable for analysis by X-ray diffraction. To probe whether 2 exists as a monomer or dimer (like 1) in solution, we resorted to convection-corrected Diffusion Ordered Spectroscopy (ccDOSY-NMR). This showed that 2 is monomeric in solution (see ESI Section 1.4), similar to a recently reported structurally related NHGe reported by He et al. We subsequently explored the introduction of metals into the empty binding pocket of 2. The addition of an equimolar amount of ZnCl 2 to a THF solution of 2 yielded a dark red/purple solution (Scheme 3) from which 3 was isolated in 68% yield. Analysis of the 1 H-NMR spectrum (THF-d 8 , see ESI Section 1.5) revealed two singlets, integrating to one proton each, at δ = 8.25 and 6.97 ppm, consistent with an aldimine and a methine proton. These chemical shifts are in agreement with one reduced binding pocket and one pocket retaining its iminopyridine character. Remarkably, the most downfield naphthyridine resonance out of the four is observed as a broad resonance lacking multiplicity rather than the expected doublet. A similar effect is observed for one of the two methine resonances of one of the dipp substituents at δ = 3.15 ppm. These observations are indicative of a dynamic change in speciation, with exchange being in the intermediate/fast regime on the timescale of the NMR experiments. In line with this interpretation, sharpening of the broad resonances in the 1 H spectrum is observed upon recording the spectra at higher temperatures (see ESI Figures ). Similarly, peak broadening and decoalescence of peaks is observed upon cooling the sample in the spectrometer in increments to 193 K (see ESI Figures ). Interestingly, upon removal of the THF solvent, 3 changes colour to blue. This colour is observed for the solid-state, as well as in the solution-state for aromatic solvents and dioxane. Analysis of the 1 H-NMR spectrum of 3 in C 6 D 6 (see ESI Figure ) revealed sharper resonances, suggesting that the observed fluxionality is likely induced by reversible THF coordination to the Zn centre, potentially followed by dissociation of the N-dipp sidearm. Scheme 3: Complexation of ZnCl 2 to the empty pocket of 2, yielding 3.