Wydział Chemii

Agnieszka Wojciechowska

Jan Janczak

Katarzyna N. Jarzembska

Tomasz Rojek

András Gorzsás

Ülo Kersen

Tomasz K. Olszewski

Julia Jezierska

2023

Polyhedron

230

116210/1-116210/11

10.1016/j.poly.2022.116210

Naukowa

Angielski

Artykuł

Two copper(II) chelidamate compounds with 2,2'-bipyridine were obtained as crystals [Cu(Hcda)(bpy)(H₂O)]∙2H₂O (1) and [Cu(H₂cda)(bpy)(H₂O)](H₂cda) (2) (H₃L = H₃cda = chel = chelidamic acid, bpy = 2,2′-bipyridine) through one-pot synthesis. In 1, the tridentate Hcda²⁻ ligand, an enol tautomer of the 4-hydroxypyridine type, and a bpy molecule coordinate the Cu(II). In 2, the same tautomer of the tridentate H₂cda⁻ ligand (with one deprotonated carboxylic acid), along with bpy, forms a cationic [Cu(H₂cda)(bpy)(H₂O)]⁺ complex. It is charge-balanced by an H₂chel⁻ anion, featuring the rare keto tautomer of the 4-pyridone type. The alternately protonated and deprotonated carboxylic groups of both tautomers are involved in hydrogen bonds leading to 1D chains. The adjacent chains are connected to form 2D chain by hydrogen bonds between two different tautomers of chel. As confirmed by the DFT calculations, the crystal structures of 1 and 2 are mainly stabilised by hydrogen bonds and electrostatic interactions, the latter being especially noticeable in the [Cu(H₂cda)(bpy)(H₂O)]⁺ cationic complex (2). Additionally, π⋯π stack is formed between aromatic ring fragments. The presence of each particular tautomer in the crystal structures of 1 and 2 can be explained by the relative energies of the respective structural moieties in the aqueous environment, combined with coordination and intermolecular interaction preferences.

Tautomers of chelidamic acid, Copper(II) complexes, Crystal structures, Spectroscopy (FT-IR, Raman, NIR-Vis-UV, EPR), Theoretical calculations

http://dx.doi.org/10.1016/j.poly.2022.116210

http://www.elsevier.com