Prototropic tautomerism of (E)-N-((4-((2-hydroxy-5-methoxybenzylidene) amino)phenyl)sulfonyl)acetamide and its coordination abilities towards Ru, Rh, and Ir trivalent metal ions

The Schiff base (E)-N-((4-((2-hydroxy-5-methoxybenzylidene)amino)phenyl)sulfonyl) acetamide (ScB-SAM) has been synthesized bytheir condensation at room temperature in ethanol. X-ray crystallographic analysis revealed that the keto-enol tautomerism of its solid state exists as a complex equilibria system that is stabilized intramolecular hydrogen bond. The enol, keto and mixed enol-zwitterionic forms were observed in the crystal structure. The crystallographic results were supported by ATR, and UV-Vis. Physical properties were determined in different polar and nonpolar solvents and solid state. All above experimental results were then compared with DFT calculations. Additionally, the stabilities of the trivalent: iridium, rhodium and ruthenium ions complexes with ScB-SAM have also been investigated by spectrophotometric titration methods in water. The data showed that the examined coordination compounds were stable in solution based on the values of their stability constants found.

Automated summary

A new Schiff base molecule, ScB-SAM, was synthesized and its solid state keto-enol tautomerism was found to exist as a complex equilibrium system. Experimental results were supported by computational calculations. The stability of complexes formed between ScB-SAM and trivalent metal ions in water solution was also confirmed through spectrophotometric titration methods.