Ultimately, we wondered if the reversibly formed azuleno[1,2c]pyran motif in 13b can be altered or interacted with a metal ion. We selected cobalt's heavier analogue and reacted 13 with [RhCl(CO)2]2 (Scheme 6). The instantaneous reaction leads to an asymmetric aromatic compound (15), in which the substituent is present in the keto form, with protons shielded to -1.83, -2.46 ppm for, now, diastereotopic CH2 and 0.12 ppm for CH3 (Fig. ). As observed above, enhanced diatropicity suggests that the species is cationic. We can also see an NH proton signal at 2.44 ppm. Two other nitrogen atoms coordinate to a rhodium(I) centre, forming a side-on coordination motif supplemented by two carbonyl groups. It was also confirmed with HRMS and C NMR studies (Fig. ). This means there was no activation of the C(21) substituent in this case, although only one (keto) tautomer was selected for coordination due to protonation. A major orange-brown band was obtained when we tried to purify deep pink 15 using basic alumina TLC. It gives the same HRMS peak, thus suggesting isomerisation. The isolated compound ( ) is still asymmetric and has no signals below 0 ppm in 1 H NMR (Fig. ). The acetone moiety gives two signals integrating 1:3 at 2.38 and 0.94 ppm, respectively. We can learn from HMBC (Fig. ) that, also in this case, the azuleno[1,2- c]pyran motif forms and one meso is rehybridised to C(sp ). This time, in contrast to 13, 16 exists as a single species. It shows that even if the spectral properties can be altered by attaching a Rh(CO)2 fragment, the main keto-enol tautomerisation can still occur. Eventually, we tried to deacidify the rhodium insertion reaction environment, namely, react [RhCl(CO)2]2 with 13 and the NaOAc addition at a slightly elevated temperature of boiling dichloromethane. This led to the acquisition of a symmetric species (17). The acetone moiety shifts to -0.61 ppm for the methyl group and -2.74 ppm for CH2, which is observed as a doublet with a 2.4 Hz coupling constant (Fig. ). This coupling comes from interactions with an NMR-active rhodium nucleus (s = 1/2) is also observed in the C NMR spectrum (14.8 ppm, JRh-C 23.4 Hz; Fig. ) reflecting the activation of the C(21)-acetone bond with the transfer of the substituent directly to the axial position of the rhodium(III) centre in the cavity. This reproduces acetone activation by rhodium(III) β-substituted azuliporphyrin and closes the cycle of transformations enforced by the confinement of metal ions in the macrocyclic cavity with the exposed carbon atom.