Solid-State Ring-Opening Structural Transformation in Triazolyl Ethanesulfonate Based Silver Complexes

Synthesis and crystal structures of distinctive examples of cage-like silver complexes [Ag₆L₆]·9H₂O (1) and [Ag₆L₆(H₂O)₄]·4H₂O (2) (L^– = 2-(4H-1,2,4-triazol-4-yl)­ethanesulfonate) are reported. Both undergo solid-state structural transformation to the one-dimensional polymeric complex [AgL]_n (3) via a ring-opening process. This transformation is initiated by the release of lattice water molecules and involves opening of nine-membered Ag₃N₆ rings via bond breaking followed by rearrangement of the Ag⁺ coordination sphere by formation of new bonds. These structural transformations were studied by thermogravimetric analysis and single-crystal and powder X-ray diffraction methods. Formation of compounds 1, 2, and {[AgL]·1.5 H₂O}_n (4) with the same Ag⁺/L^– ratio but different crystal structures depends on the concentration and acidity of the reaction mixture. Furthermore, ligand conformation and trz-Ag-trz placement (trans, cis, gauche) are important for the connectivity and formation of the coordination polymers.