Di(4-pyridyl) sulfoxide as an angled building block for zigzag-chain silver(I) complexes stabilized by supramolecular O=S⋯π interactions

Abstract

<p>The angled ligand di-4-pyridyl sulfoxide (L₁) and five of its silver(I) complexes that bear various counteranions, namely, {[Ag(L ₁)](BF₄)·(CH₃CN)}_∞ (1), {[Ag(L₁)(CF₃SO₃)]·(CH ₃CN)}_∞ (2), {[Ag(L₁)(CF ₃CO₂)]·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 1-5 exhibit a common [Ag(L ₁)]_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 L ₁ ligand plays a crucial role in the supramolecular aggregation of 1-5. Replacement of the sulfinyl (S=O) group of L₁ by a sulfonyl (O=S=O) group to yield related ligand L₂ led to {[Ag(L ₂)](NO₃)}_∞ (6) (L₂ = di-4-pyridyl sulfone), which exhibits a markedly different supramolecular architecture from those of 1-5 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. <br></p>