Gem‐diol generation in copper and zinc N‐methyl‐2‐imidazolecarboxaldehyde complexes: solid‐state NMR, EPR and single‐crystal X‐ray studies

CRESPI, AYELÉN F.; VEGA, DANIEL; PÉREZ, ANA L.; RODRÍGUEZ-CASTELLÓN, ENRIQUE; LÁZARO-MARTÍNEZ, JUAN MANUEL

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Año: 2023

1434-1948

Three novel coordination compounds, a mono- (1) and binuclear copper complexes (2) and a zinc complex (3) were synthesized and studied through single-crystal X-ray crystallography, solid-state NMR and EPR techniques to get the chemical functionalization of the carbonyl group in N-methyl-2-imidazolecarboxaldehyde. Particularly, molecules containing carbonyl groups (aldehydes and ketones) are versatile ligands that give rise to a wide range of new materials, due to the reactivity of the carbonyl group when it is attached to pyridine or imidazole derivatives. However, the chemical identification of the functional group present in these coordination compounds is usually a challenge since the copper ion affects the NMR signals and it is where X-ray crystallography becomes indispensable. For the copper complexes 1 and 2, the imidazole ligand was elucidated as the aldehyde and the gem-diol forms, respectively.In addition, the composition of polycrystalline samples obtained from the same synthetic rout, used to obtain the single crystal materials, were studied by solution- and solid-state NMR experiments. Particularly, complex 3 showed significant differences between the structure resolved by X-ray and the composition of the polycrystalline sample analyzed by NMR.