Axially chiral bis-1,2,3-Triazol-4-ylidene–Ag(I)-MIC and, bis-Au(I)-MIC complexes of (R)-BINOL and (-)-Menthol scaffold: Synthesis, structure, and characterizations

Abstract

Herein, we report the novel axially chiral bis-Ag(I)-MIC and, bis-Au(I)-MIC complexes bearing axially chiral bis-1,2,3-triazolium-derived mesoionic carbene (tz-MIC) ligands were synthesized. The enantiopure R-BINOL was employed as a basic unit to synthesize a axially chiral bis-1,2,3-triazolium-derived mesoionic carbene (tz-MIC) ligands (1–2)a. In particular, the axially chiral bis-1,2,3-triazolium-derived mesoionic carbene (tz-MIC) ligands (1–2)a, were obtained from the reaction of corresponding bis-1,2,3-triazole ligand precursor with methyl and ethyl iodide in 82−90% yields. Novel axially chiral bis-Ag(I)-MIC complexes (1 − 2)b, were prepared by the treatment of corresponding axially chiral bis-1,2,3-triazolium-derived mesoionic carbene (tz-MIC) iodide salts, (1 − 2)a, with Ag2O via in-situ deprotonation method in 69−86% yields. Novel axially chiral bis-Au(I)-MIC complex-2c was synthesized from their respective novel axially chiral bis-Ag(I)-MIC complex-2b, using transmetallation reaction with (SMe2)AuCl in 70% yield. All these novel axially chiral bis-Ag(I)-MIC and bis-Au(I)-MIC complexes were isolated for the first time and structurally characterized by 1H NMR and 13C{1H}-NMR spectroscopy, FT-IR spectroscopy, mass spectrometry, elemental analysis, specific optical rotation and, single crystal X-ray crystallography.