Silver(i) coordination polymers of trans-5-styrylpyrimidine – from structural diversity to solid-state reactivity under sunlight

Abstract

Reactions of a photostable bidentate ligand trans-5-styrylpyrimidine (5-Spym) with various silver(I) salts resulted in the formation of coordination polymers (CPs) of composition {[Ag(5-Spym)(H₂O)](NO₃)} (1), {[Ag(5-Spym)(H₂O)](BF₄)} (2), {[Ag(5-Spym)](SbF₆)} (3), {[Ag(5-Spym)(CF₃SO₃)]} (4), and {[Ag(5-Spym)(CF₃CO₂)]} (5). The first four CPs (1–4) were found to be one-dimensional (1D) zigzag coordination polymers, where 5-Spym ligands from the neighbouring chains assembled in an infinite parallel arrangement in a head-to-tail fashion. These CPs exhibited [2 + 2] photocycloaddition reaction in the solid state upon exposure to sunlight. On the other hand, the structure of 5 was determined to be a two-dimensional (2D) coordination polymer, and it was found to be photostable. In these series of compounds, the coordination number of Ag(I) varied from 2 to 4, and the coordination geometries were observed to be linear, T-shaped, trigonal, square planar and distorted tetrahedral. By varying the counteranions in the silver(I) salts, various coordination numbers and geometries, and thus structural diversity, and various solid-state photo-reactivities were observed. The scope of mechanochemistry in accessing these CPs is also discussed. Various types of intermolecular interactions observed in this series of compounds have been verified by analyses of their Hirshfeld surfaces.