Synthesis and Characterization of Silver(I) Coordination Networks Bearing Flexible Thioethers:  Anion versus Ligand Dominated Structures

This report describes the synthesis and X-ray characterization of a series of LⁿAgX complexes wherein Lⁿ = PhS(CH₂)_nSPh (n = 2, 4, 6, 10) and X = CF₃SO₃^-, CF₃COO^-, CF₃CF₂COO^-, CF₃CF₂CF₂COO^-, NO₃^-, and ClO₄^-. This study was undertaken in order to rationalize the structure of the coordination networks formed as a function of the anion coordinating strength and the ligand structure. The following complexes were examined:  with L², CF₃SO₃^- (1), CF₃COO^- (2), ClO₄^- (3); L⁴, CF₃SO₃^- (4), CF₃COO^- (5), CF₃CF₂COO^- (6), CF₃CF₂CF₂COO^- (7); L⁶, CF₃COO^-·H₂O (8), CF₃CF₂COO^- (9), CF₃CF₂CF₂COO^- (10); and L¹⁰, NO₃^- (11). The anions selected are classified in three groups of increasing coordinating strength:  perchlorates, fluorosulfonates, and perfluorocarboxylates. Except in two cases, all complexes form 2D-coordination networks. The 2D-network in 1 (L², CF₃SO₃^-) is made up of Ag(I) and L², while the anion is only a terminal co-ligand that completes the trigonal coordination around Ag(I). In 4 (L⁴, CF₃SO₃^-), a 1D-coordination polymer, [Ag−L⁴−]_∞, is observed where the anions are coordinated to Ag(I) in a trigonal fashion. The perfluorocarboxylates form tetrameric units in a zigzag shape, but only with the L⁴ ligand. In these (6 and 7), the silver−silver distances are very short, especially those of the central bond, indicating the presence of weak Ag−Ag interactions. Dimers, with short silver−silver distances, are observed with ligands L² and L⁶ and perfluorocarboxylates. In 8 (L⁶, CF₃COO^-·H₂O), a 3D channel-like structure is built through water molecules that connect adjacent layers. An unusual stoichiometry is noted in 3 (L², ClO₄^-, acetone); Ag:L is 4:2.5. In 11 (L¹⁰ and NO₃^-), the nitrate acts as a bidentate ligand and an [Ag−NO₃−]_∞ chain is formed. Adjacent chains are linked by the L¹⁰ ligands into a 2D-coordination network.