Pyridine-2-thione (pySH) derivatives of silver(I): Synthesis and crystal structures of dinuclear [Ag2Cl2(μ-S-pySH)2(PPh3)2] and [Ag2Br2(μ-S-pySH)2(PPh3)2] complexes

Reaction of silver(I) halides with PPh3 in acetonitrile and then with pyridine-2-thione (pySH) chloroform (1:1:1 molar ratio) has yielded sulfur bridged dimers of general formula, [Ag2X2(μ-S-pySH)2(PPh3)2] (X = Cl, 1, Br, 2). Both these complexes have been characterized using analytical data, NMR spectroscopy and single crystal X-crystallography. The central Ag2S2 cores form parallelograms with unequal Ag–S bond distances (2.5832(8), 2.7208(11) Å) in 1 and (2.6306(4), 2.6950(7) Å) in 2, respectively. The Ag⋯Ag contacts of compounds 1 and 2 are 3.8425(8) and 3.8211(4) Å, respectively. The angles around Ag (in the range 87.19(2)–121.71(2)° in 1 and 87.81(2)–121.53(2)° in 2) reveal highly distorted tetrahedral geometry. There are inter dimer π–π stacking interactions between pyridyl rings (inter ring distances of 3.498 and 3.510 Å in complexes 1 and 2, respectively). The solution state 31P NMR spectroscopy has shown the existence of both monomers and dimers. The studies reveal relatively weaker intramolecular –NH⋯Cl hydrogen bonding in case of AgCl vis-à-vis that in CuCl which favored both a monomer and a dimer with AgCl, and only a monomer with CuCl.

Graphical abstractPyridine-2-thione has yielded dinuclear complexes with silver(I) chloride/bromide in presence of PPh3 (1 and 2).Figure optionsDownload full-size imageDownload as PowerPoint slide