Fine competition and control among argentophilic, electrostatic, and π···π interactions in a molecular chair structure

Abstract

The reaction of AgX (X -= NO 3 -, ClO 4 -, or CF 3 SO 3 -) with 1,3-bis(3-pyridyl)tetramethyldisiloxane (L) at room temperature affords 20-membered metallacyclodimers, [Ag(L)] 2 (X) 2 . For the macrocyclodimer, fine competition among argentophilic, electrostatic, and pÁÁÁp interaction exists. The macrocyclodimer is a unique molecular chair that tunes a transannular argentophilic interaction via the bite size of the counteranions. In order to reversibly control the argentophilic interaction, anion exchange has been accomplished. The anion exchangeability depends on the water solubility rather than the electrostatic interaction between silver(I) and anions.

Argentophilic Interactions

“…The 24‐ and 26‐membered rings ( 100 , E=O or CH 2 CH 2 ) have Ag–Ag distances of 3.231(4), 3.283(1), and 3.321(1) Å in the 24‐membered rings (depending on the nature of the anion NO 3 − , ClO 4 − , CF 3 SO 3 − ) and 3.243(1) and 3.346(1) Å (two independent dimers of the perchlorate) in the 26‐membered rings. It is important to note that in all these cases the metal atoms are significantly closer to each other than the π–π stacked pyridine rings 320–322. In the large dimetallamacrocycles produced by the coordination of AgOSO 2 CF 3 or AgPF 6 to a cyclotetraphosphazene bearing pyridinoxy substituents, the folding of the ring depends on the position of the pyridine nitrogen atoms: With 3‐pyridinoxy groups, Ag–Ag contacts of 3.199(2) are established across two 20‐membered rings, while with 4‐pyridinoxy groups the two silver atoms are kept further apart owing to the ligand constraints.…”

“…It is important to note that in all these cases the metal atoms are significantly closer to each other than the p-p stacked pyridine rings. [320][321][322] In the large dimetallamacrocycles produced by the coordination of AgO-SO 2 CF 3 or AgPF 6 to a cyclotetraphosphazene bearing pyridinoxy substituents, the folding of the ring depends on the position of the pyridine nitrogen atoms: With 3-pyridinoxy groups, Ag-Ag contacts of 3.199(2) are established across two 20-membered rings, while with 4-pyridinoxy groups the two silver atoms are kept further apart owing to the ligand constraints. Therefore, only an intermolecular contact of 3.408 is established (101).…”