Novel dithioether-silver(I) coordination architectures: structural diversities by varying the spacers and terminal groups of ligands

An investigation into the dependence of the framework formation of coordination architectures on ligand spacers and terminal groups was reported based on the self-assembly of AgClO4 and eight structurally related flexible dithioether ligands, RS(CH2)(n) SR (La-n, R = ethyl group; L-b(n), R = benzyl group, n = 1 4). Eight novel metal organic architectures, [Ag(L-a(1))(3/2)ClO4](n) (1a), [Ag-2(L-a(2))(2)(ClO4)(2)](2) ( 2a), [AgLa3 ClO4] n ( 3a), {[Ag(L-a(4))(2)] ClO4}(n) (4a), [AgLb1 ClO4](2) (1b), [Ag(L-b(2))(2)]ClO4 ( 2b), {[Ag(L-b(3))(3 /)2(ClO4)(1/2)] (ClO4)(1/2)}(n) (3b) and [Ag(L-b(4))(3 /2)ClO4](n) (4b), were synthesized and structurally characterized by X-ray crystallography. Structure diversities were observed for these complexes: 1a forms a 2-D ( 6,3) net, while 2a is a discrete tetranuclear complex, in which the Ag-I ion adopts linear and tetrahedral coordination modes, and the S donors in each ligand show monodentate terminal and mu(2)-S bridging coordination fashions; 3a has a chiral helical chain structure in which two homo-chiral right-handed single helical chains (Ag L-a(3)-)(n) are bound together through mu(2)-S donors, and simultaneously gives rise to left-handed helical entity ( Ag S)(n). In 4a, left- and right-handed helical chains formed by the ligands bridging Ag-I centers are further linked alternately by single-bridging ligands to form a non-chiral 2-D framework. 1b has a dinuclear structure showing obvious ligand-sustained Ag Ag interaction, while 2b is a mononuclear complex; 3b is a 3-D framework formed by ClO4 linking the 2-D ( 6,3) framework, which is similar to that of 1a, and 4b has a single, double-bridging chain structure in which 14-membered dinuclear ring units formed through two ligands bridging two Ag-I ions are further linked by single-bridging ligands. In addition, a systematic structural comparison of these complexes and other reported AgClO4 complexes of analogous dithioether ligands indicates that the ligand spacers and terminal groups take essential roles on the framework formation of the Ag I complexes, and this present feasible ways for adjusting the structures of such complexes by modifying the ligand spacers and terminal groups.