Silver(I)-polynitrile network solids for anion exchange: Anion-induced transformation of supramolecular structure in the crystalline state

Novel supramolecular solids whose topologies depend on the counteranion, [Ag(C₁₄H₂₀N₆)(NO₃)] (1), [Ag(C₁₄H₂₀N₆)]CF₃SO₃ (2), and [Ag(C₁₄H₂₀N₆)]ClO₄ (3), have been prepared by the self-assembly of AgX (X = NO₃^-, CF₃SO₃^-, and ClO₄^-) with ethylenediaminetetrapropionitrile (EDTPN,C₁₄H₂₀N₆). X-ray crystal structures indicate that compounds 1-3 are a 1-D coordination polymer, a 2-D layer, and a boxlike 2-D network, respectively. In 1, 2, and 3, the EDTPN ligand undergoes anion-dependent ligation to bind two, three, and five Ag(I) ions per EDTPN, respectively, by using the cyano groups in addition to two tertiary nitrogen atoms. The coordination numbers of Ag(I) ion in 1, 2, and 3, are five, four, and six, respectively. Interestingly, the CF₃SO₃^- anion of 2 is exchanged with NO₃^- and ClO₄^- quantitatively in the crystalline state when the crystal of 2 is immersed in the aqueous solutions of NaNO₃ and NaClO₄, respectively. The anion-exchange process is reversible between 1 and 2 but irreversible from 1 or 2 into 3. The supramolecular structural transformations among 1-3 are observed in the crystalline state, concomitant with the anion-exchange.