Synthesis and structure of Zn(II) and Cu(II) complexes derived from 2-(aminomethyl)benzimidazole and glycine

Abstract

2014) Synthesis and structure of Zn(II) and Cu(II) complexes derived from 2-(aminomethyl)benzimidazole and glycine, Reactions of 2-(aminomethyl)benzimidazole di-hydrochloride (1·2HCl) and glycine with 3Zn (OH) 2 ·2ZnCO 3 or Cu(OAc) 2 ·H 2 O led to the synthesis of the quaternary coordination complexes 2 and 3. X-ray diffraction showed that these complexes are composed of 2a = [Zn(L)Cl(L′)] and 2b = [Zn(L)(H 2 O) 2 (L′)], and of 3a = [Cu(L)(H 2 O) 0.25 Cl(L′)] and 3b = [Cu(L)(H 2 O) 1.5 (L′)], respectively, where L = 2-(aminomethyl)benzimidazole and L′ = glycinate. Zn(II) in 2a has an intermediate geometry between a square-pyramid and a trigonal bipyramid structure.However, the geometry about the metal ion of units 2b, 3a, and 3b is distorted octahedral. Moreover, the supramolecular structures for 2 and 3 were assembled through N-H⋯O and O-H⋯Cl hydrogen bonds. In these complexes, H 2 O and N-H groups serve as proton donors, whereas chloride and C=O groups serve as proton acceptors. Also π-π stacking interactions between aromatic rings contribute to the stabilization of the supramolecular structure of 2 and 3. The Zn and Cu complexes were studied by infrared and Raman spectroscopy, which indicated that 2 and 3 have similar molecular structures in the solid state. Ultrasound activation at the end of the reaction was necessary to yield 2.

Coordinating Ability of Anions, Solvents, Amino Acids, and Gases towards Alkaline and Alkaline‐Earth Elements, Transition Metals, and Lanthanides

“…For the analysiso ft he coordinating ability of the 21 natural amino acids we can concentrate first on their anionic forms with carboxylato groups. Althoughi nm ost cases the amino carboxylates appear coordinated to at ransition metal atom in all structures in which the two species coexist, there are af ew exceptions.F or glycinate, six uncoordinated structures were found;o ft hem, two indeedc orrespond to the amino-carboxylate anion [96][97] coordinated to coppera toms, ac onnectivity that is not disclosed by the CSD, but that was recovered in the categoryof"semi-coordinated" structures;the other four correspond to lanthanide-containing poly-oxotungstates in which the glycinate ion is coordinated to the lanthanide in am onodentate fashion rather than to the tungsten atoms. [98] Also in the case of histidinate, in the only two structures in which its anion is not coordinated to an earbyt ransition metal,i ti s bound to al anthanide.…”