Aldehyde coordination in template reactions: Crystal structure of a possible reaction intermediate

Generation and Stability of the gem-Diol Forms in Imidazole Derivatives Containing Carbonyl Groups. Solid-State NMR and Single-Crystal X-ray Diffraction Studies

“…These differences are due to the specific electronic density of the imidazole ring positions; that is, one of the nitrogen atoms is mesomeric electron-donating (N 1 ), and the other one is electron-withdrawing (N 3 ) . Taking into account these results, it can be postulated that the lower reactivity of the aldehyde group in A 3 toward the addition of water would explain why in copper, cadmium, zinc, and cobalt complexes the formyl group remains unhydrated. , The same results have been obtained for a complex of zinc­(II) and A 4 . An iron­(III) complex was also reported with a new 4-imidazolecarboxaldehyde ligand in which the formyl group was not altered .…”

“…21,40 The same results have been obtained for a complex of zinc(II) and A 4 . 23 An iron(III) complex was also reported with a new 4-imidazolecarboxaldehyde ligand in which the formyl group was not altered. 41 In contrast, the aldehyde group is hydrated to the gem-diol form in ruthenium-(III) complexes with 2-imidazolecarboxaldehyde (A 1 ) molecules in the solution state.…”

“…Among the wide variety of heterocyclic aldehydes used as chelating ligands, the imidazolecarboxaldehyde isomers − and pyridinecarboxaldehyde compounds − ,,,, are relevant due to their potential capacity to remove toxic metals from the body . In this context, we previously reported the isolation of the neutral gem -diol form of the 2-imidazolecarboxaldehyde in the solid state .…”