Anion effects on the formation of cross-linked argentophilic interaction. Synthesis and structural properties of AgX bearing bis(3-pyridyl)dimethylsilane (X^- = CF₃SO₃^-, PF₆ ^-, and NO₃^-)

Anion effects on the formation of a cross-linked Ag-Ag interaction in the molecular construction of a series of AgX complexes with bis(3-pyridyl) dimethylsilane (L) (X^- = CF₃SO₃^-, PF₆^-, and NO₃^-) have been carried out. The slow diffusion of an organic solution of L into an aqueous solution of AgX afforded [Ag(L)]X or [Ag(X)(L)]. Each L connected two Ag(I) ions (Ag-N = 2.110(5)-2.161(4) Å) to form a wave strand. For CF₃SO ₃^- and PF₆^- anions, each single strand cross-linked the adjacent single strands via an argentophilic interaction (Ag-Ag = 3.0551(7) Å for CF₃SO₃^-, 3.279(1) Å for PF₆^-) to produce unique 2D sheets. In contrast, for the NO₃^- anion, the anion acts as a ligand (Ag-O₃N = 2.61-2.79 Å) instead of the argentophilic interaction (Ag⋯Ag = 3.351(1) Å). That is, a small coordinating anion is an obstacle to form the argentophilic interaction, whereas a big noncoordinating anion favors the argentophilic interaction in the present molecular construction. For all complexes, the geometry around the Ag(I) ion is a typical T-shaped arrangement. The thermal stability can be explained in terms of the structural properties, including the argentophilic interaction.