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

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posted on 2006-02-20, 00:00 authored by Mohamed Osman Awaleh, Antonella Badia, François Brisse, Xian-He Bu
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.