Di(4-pyridyl) Sulfoxide as an Angled Building Block for Zigzag-Chain Silver(I) Complexes Stabilized by Supramolecular O=S···π Interactions



The angled ligand di-4-pyridyl sulfoxide (L1) and five of its silver(I) complexes that bear various counteranions, namely, {[Ag(L1)](BF4)·(CH3CN)} (1), {[Ag(L1)(CF3SO3)]·(CH3CN)} (2), {[Ag(L1)(CF3CO2)]·CH3CN} (3), {[Ag(L1)(NO3)]·H2O} (4), and {[Ag2(L1)2(SO4)]·6H2O} (5), have been synthesized and characterized by X-ray crystallography, FTIR spectroscopy, elemental analysis, and luminescent emission measurements. Complexes 15 exhibit a common [Ag(L1)]nn+ zigzag-chain motif generated by the μ2-N,N-bridging L1 ligand. The common dominant intermolecular O=S(sulfinyl)···π(pyridyl) interaction with the S=O group embraced by the pyridyl wings of an adjacent butterfly-like L1 ligand plays a crucial role in the supramolecular aggregation of 15. Replacement of the sulfinyl (S=O) group of L1 by a sulfonyl (O=S=O) group to yield related ligand L2 led to {[Ag(L2)](NO3)} (6) (L2 = di-4-pyridyl sulfone), which exhibits a markedly different supramolecular architecture from those of 15 because of the absence of the O=S(sulfinyl)···π(pyridyl) contact. Density functional calculations confirm that there is a π orbital interaction between the sulfinyl S atom and the intermolecular pyridyl rings, which significantly contributes to the O=S···π affinity.