Assembly of Soft Metal Complexes of an O₄S₂‑Macrocycle Displaying Endocyclic Monomer, Dumbbell-Like Dimer, and Endo-/Exocyclic Polymer Structures

A comparative investigation of the coordination behavior of an O₄S₂-donor macrocycle <b>L</b> with the thiaphilic soft metal ions Ag⁺, Cu⁺, Hg²⁺, and Pd²⁺ is reported. The X-ray structures of seven complexes (<b>1</b>–<b>7</b>) have been determined, and a range of structural types and coordination modes, including discrete to continuous forms, mono- to multinuclear, and endo- to exocyclic structures involving M–S bonds, are presented. First, reactions of <b>L</b> with AgClO₄, Hg­(NO₃)₂, and K₂PdCl₄ afforded the typical endocyclic 1:1 complexes [Ag<b>L</b>]­ClO₄ (<b>1</b>) without anion binding, as well as [Hg<b>L</b>(NO₃)₂] (<b>2</b>), and [Pd<b>L</b>Cl₂] (<b>3</b>), with anion binding. Further reaction of the anion-free complex <b>1</b> with different spacer ligands (<b>L′</b>: dabco = 1,4-diazabicyclo[2.2.2]­octane and bpp = 1,4-bis­(4-pyridyl)­piperazine) resulted in the formation of the interesting “dumbbell”-like complexes [Ag₂<b>L</b>₂(dabco)]­(ClO₄)₂ (<b>4</b>) and [Ag₂<b>L</b>₂(bpp)]­(ClO₄)₂ (<b>5</b>), exhibiting a [(<b>L</b>Ag)-<b>L′</b>-(Ag<b>L</b>)] arrangement, respectively. Furthermore, the straightforward one-pot reactions of <b>L</b> with AgClO₄ in the presence of <b>L′</b> also resulted in the isolation of the corresponding “dumbbell” complexes. Comparative NMR studies suggest the existence of corresponding structures of this type in solution. Contrasting with the discrete structures of <b>1</b>–<b>5</b>, reactions of <b>L</b> with CuBr and AgSCN afforded a double-stranded 1D network {[(Cu₂Br₂)<b>L</b>₂]·2CH₂Cl₂}_<i>n</i> (<b>6</b>) linked with a rhomboidal Cu₂Br₂ cluster and an endo-/exocyclic 1D network [Ag₄<b>L</b>₂(SCN)₄]_<i>n</i> (<b>7</b>), respectively. The latter complex features an unusual fishbone-like structure in which endocyclic silver­(I) complexes are attached to a “looped” exocyclic backbone of type {Ag-(1,3-μ₂-SCN)₂-Ag-(1,1,3-μ₃-SCN)-Ag}_<i>n</i> via Ag-SCN bonds