Discrete and infinite 1D, 2D/3D cage frameworks with inclusion of anionic species and anion-exchange reactions of Ag3L2 type receptor with tetrahedral and octahedral anions

Abstract

Complexes [PF₆⊂(Ag₃(titmb)₂](PF₆)₂ (8) and {SbF₆⊂[Ag₃(titmb)₂](SbF₆)₂}·H₂O·1.5 CH₃OH (9) are obtained by reaction of titmb and Ag⁺ salts with different anions (PF₆⁻ and SbF₆⁻), and crystal structures reveal that they are both M₃L₂ cage complexes with short Ag⋯F interactions between the silver atoms and the fluorine atoms of the anions. In complex 8, a novel cage dimer is formed by weak Ag⋯F contacts; an unique cage tetramer formed via Ag⋯π interactions (Ag⋯η⁵-imidazole) between dimers and an infinite 1D cage chain is presented. However, each of the external non-disordered SbF₆⁻ anions connect with six cage 9s via Ag⋯F contacts, and each cage 9 in turn connects with three SbF₆⁻ anions to form a 2D network cage layer; and the layers are connected by π–π interactions to form a 3D network. The anion-exchange reactions of four Ag₃L₂ type complexes ([BF₄⊂(Ag₃(titmb)₂](BF₄)₂ (6), [ClO₄⊂(Ag₃(titmb)₂](ClO₄)₂ (7b), [PF₆⊂(Ag₃(titmb)₂](PF₆)₂ (8) and [SbF₆⊂(Ag₃(titmb)₂](SbF₆)₂·1.5CH₃OH (9)) with tetrahedral and octahedral anions (ClO₄⁻, BF₄⁻, PF₆⁻ and SbF₆⁻) are also reported. The anion-exchange experiments demonstrate that the anion selective order is SbF₆⁻ > PF₆⁻ > BF₄⁻, ClO₄⁻, and this anion receptor is preferred to trap octahedral and tetrahedral anions rather than linear or triangle anions; SbF₆⁻ is the biggest and most preferable one, so far. The dimensions of cage complexes with or without internal anions, anion-exchange reactions, cage assembly and anion inclusions, silver(I) coordination environments, Ag–F and Ag–π interactions of Ag₃L₂ complexes 1–9 are discussed.