Nature of S→M Bond in some Pharmaceutical Complexes of Group 11Metals

N-heterocyclic carbenes are well known σ-donor and their coordination chemistry with transition elements, particularly group 11 metals, would be noticeable. The first stable Nheterocyclic carbene (NHC) was synthesized by Arduengo et al. in 1991. Nowadays metal-NHC complexes appear as an emerging field of research on the development of novel metallodrugs because of their high stability and ease of derivatization. This study seeks to characterize the structure and nature of S→M bond in somepharmaceuticalcomplexes of group 11 metals (M= Cu(I), Au(I), Ag(I)) in coordination with S atom of 3,4,5- three -O-acetyl-2 methyl acetato-1thio- ꞵ- D-pyranosato (Tgt) with general formula[Tgt→MNHC(R)] {M= Cu(I), Au(I), Ag(I), R= F, Cl, Br, H, CH3, SiH3 and 2,6 diisopropyl phenyl} at the Pbe/def2 TZVP level of theory. The strength and nature of donor−acceptorbond between the Tgt and M-NHC(R) fragments in the complexes were studied by using NBO and energy decomposition analysis (EDA), as well as their natural orbitals forchemical valence variation (EDA-NOCV). The results show that the S→M bond interaction energies is conforming the well-known V-shaped trend for the transition metals of the first, second, and third row in the following order: Ag(I) < Cu(I) < Au(I). Also result showed that the nature of the S→M bond in [Tgt→M-NHC(R)] complexes is largely electrostatic, with a contribution of about 70% interaction energy [1,2].