Unusual coordination in a silver thionate complex. Synthesis, structural characterization and theoretical calculations of dinuclear and polynuclear silver(I) thiosaccharinates with pyridine and 1,10-phenanthroline

Abstract

Treatment of Ag 6(tsac) 6 (tsac = thiosaccharinate anion) with pyridine (py) and 1,10-phenanthroline ( o-phen) each affords two novel silver(I)-thiosaccharinate complexes: dinuclear [Ag 2(tsac) 2py] ( 1) and polynuclear [Ag(tsac)( o-phen)] n ( 2). Both crystal structures have been determined by X-ray diffraction and spectroscopic structural analysis (IR and Raman, UV–Vis, 1H and 13C NMR) have also been made for both compounds. Thermal stability analysis (TGA and DTA) of complex 1 are used to confirm the strength of the pyridine coordination to the silver ion. The molecular structure of complex 1 shows some astonishing characteristics. The two silver atoms are in different environments: one of them is surrounded by two S atoms, while the other completes its coordination sphere by three N atoms, two from the thiosaccharinate anions and the third from a pyridine molecule. The short Ag(1)–Ag(2) contact distance, 2.9681(8) Å, indicates an interaction between the two silver metal atoms exists. Complex 2 shows a thiosaccharinate molecule bridging two silver atoms through the exocyclic S atom while the o-phenanthroline ligand is coordinated as a bidentate N, N chelate, forming a polynuclear chain. Quantum chemical calculations confirm the argentophilic character of the Ag–Ag interaction in complex 1, and its structure and vibrational assignments were correlated and confirmed theoretically.