Coordination structure and extraction behavior of a silver ion with N-substituted-9-aza-3,6,12,15-tetrathiaheptadecanes: significant effect of Ph–C–N framework on the extractability

Abstract

N-Substituted-9-aza-3,6,12,15-tetrathiaheptadecanes having Ph–C–N frameworks (N-R-ATH; R = benzyl (N-Bn-ATH), 4-nitrobenzyl (N-NO₂Bn-ATH), and diphenylmethyl (N-Ph₂CH-ATH)) were synthesized, and their Ag(I) complexes were structurally characterized. X-Ray crystal structure analyses of [Ag(N-R-ATH)](BF₄) (R = Bn and Ph₂CH) revealed monomeric tetra-S-coordinated complex cation structures without the N-coordination, and a benzene ring of the N-R group covered over the amine nitrogen atom. The precise extraction analyses of a Ag(I) ion with ATH derivatives (L = N-R-ATHs and N-H-ATH) associated with the ¹H NMR analyses of the [Ag(L)]⁺ complexes in polar and non-polar solvents revealed that the introduction of the N-substituent significantly enhanced the extractability of Ag⁺, due to the “hydrophobic cover” effect by the Ph–C–N framework in the [Ag(N-R-ATH)]⁺ complexes.