CrIII and CuI complexes of 2,2′,2-(1H-imidazole-2,4,5-triyl)-tripyridine: In situ generation of imidazole ring from the coupling of picolinaldehyde and ammonium acetate

The syntheses, characterizations and properties of two coordination complexes, [Cr-3(L)(3)Cl-6] (1) and [Cu-4(L)(2)Br-2](n) (2) (HL = 2,2',2 ''-(1H-imidazole-2,4,5-triyl)tripyridine) were reported. The HL ligand was unprecedentedly afforded by metal-mediated solverthermal in situ metal-ligand reaction among picolinaldehyde, ammonium acetate and metal ions. Compound I can be described as a bottom-opened vase-like complex with the three Cr-III ions showing a triangle conformation. For complex 2, the sandwich-like [Cu-4(L)(2)](2+) moieties are linked by bromide ions to generate a 1D chain framework Variable-temperature magnetic studies in the temperature range of 2.0-300 K for 1 reveal antiferromagnetic Cr-III center dot center dot center dot Cr-III interactions. The catalytic activity of 2 towards the reaction of 2-butanone and ethylene glycol was also investigated; it showed a very good catalytic property allowing for the easy and high yielding preparation of 2-ethyl-2-methyl-1,3-dioxolane under mild conditions. (C) 2015 Elsevier B.V. All rights reserved.