Hexafluorosilicate anion in the formation of a coordination cage: anion competition

Abstract

The construction of a coordination cage in a system of dual anions including hexafluorosilicate was investigated. The self-assembly of Cu(BF₄)₂ with L in the presence of (NH₄)₂SiF₆ gives rise to a cage of [(SiF₆)@Cu₂L₄](BF₄)₂, whereas the reaction of CuX₂ (X⁻ = NO₃⁻ and ClO₄⁻) with L in the presence of (NH₄)₂SiF₆ yields a cage of [(SiF₆)@Cu₂L₄](SiF₆). The anion exchange of [(SiF₆)@Cu₂L₄](BF₄)₂ with NaPF₆ in acetone gives rise to a 2D structure of [Cu(PF₆)₂L₂]·C₃H₆O. Significant catalytic effects on catechol oxidation catalysis in dichloromethane were observed in the order [(SiF₆)@Cu₂L₄](BF₄)₂·MeOH > [(SiF₆)@Cu₂L₄](SiF₆)·6MeOH ≫ [Cu(PF₆)₂L₂]·C₃H₆O > Cu(BF₄)₂. The oxidation catalysis reactions using the coordination cages were efficiently completed within 20 min at 40 °C, the performance of which ranks among the most efficient yet recorded.