Triflate anion and ligand influences in silver(i) coordination polymers of four isomeric dipyridyl ketone oximes

Abstract

The synthesis and X-ray characterisation of four isomeric dipyridyl ketone oxime ligands, 4,4′-dipyridyl ketone oxime, L⁴⁴, 3,3′-dipyridyl ketone oxime, L³³, 2,4-dipyridyl ketone oxime, L²⁴ and 2,3-dipyridyl ketone oxime, L²³ is described. X-ray structural characterisation of the precursor ketones 3,3′-dipyridyl ketone, L1, and 2,4-dipyridyl ketone, L2, is also reported for comparison. Four AgCF₃SO₃ complexes of the dipyridyl ketone oxime ligands were prepared and structurally characterised, [Ag(L⁴⁴)₂](CF₃SO₃), 1, {[AgL³³](CF₃SO₃)}_∞, 2, [AgL²⁴(CF₃SO₃)]_∞, 3, and [Ag₂L²³(CF₃SO₃)₂]_∞, 4. The structural role of the CF₃SO₃⁻ anion in the formation of Ag(I) coordination polymer networks, together with the effect of the varying pyridyl substitution patterns of L⁴⁴, L³³, L²⁴ and L²³ was investigated. In 1 the CF₃SO₃⁻ anion was unbound and disordered. It was encapsulated in the channels of a honeycomb 3D H-bonded structure. In 2 the CF₃SO₃⁻ anion remained unbound, being encapsulated within the centre of a helical polymer chain. In 3 the CF₃SO₃⁻ anion was weakly bound to the Ag(I) ion and as such decorated the side of a bowed 1-D chain. The two different CF₃SO₃⁻ anions in 4 adopted a range of binding modes from monodentate, bis-monodentate to tris-monodentate with the Ag(I) ions and gave rise to the formation of an unusual CF₃SO₃⁻ bridged 2-D network.