Macrocycles of axially chiral and racemic N-heterocyclic carbene silver(I), gold(I) and palladium(II) complexes: synthesis, characterization and computational structures

摘要

In this study, Ag(I), Au(I) and Pd(II) bis-N-heterocyclic carbene (NHC) complexes derived from axially chiral R-1,1'-binaphthyl-2,2'-diol (R-BINOL) and racemic biphenyl-2,2'-diol scaffolds have been synthesized. The metallation of these bis-imidazolium and bis-triazolium types of ligand precursors of R-BINOL and biphenol unit, viz. (1-4)d has been achieved using standard procedure. The {[L(L'-NHC)(2)]AgICl-type, chiral (1-2)e and racemic (3-4)e complexes have been obtained by the treatment of ligand with Ag2O. Similarly, chiral Pd(II) (11) and Au(I) (ig) complexes have been synthesized and analysed using spectroscopic techniques. The geometry-optimized structures obtained through the density functional theory display good proximity with the reported X-ray structures of similar type of Ag(I), Au(I) and Pd(II) complexes.