Anion Dependent Structures of Luminescent Silver(I) Complexes

The reaction of AgX, where X = trifluoroacetate (CF₃CO₂^-, tfa), nitrate (NO₃^-), trifluoromethanesulfonate (triflate, CF₃SO₃^-, OTf), hexafluorophosphate (PF₆^-), or perchlorate (ClO₄^-), with 2,2‘,3‘ ‘-tripyridylamine (tpa) yields five novel silver(I) complexes, which have been structurally characterized. The five complexes have the same 1:1 stoichiometry of Ag/tpa but exhibit different modes of coordination, depending upon the counterion present in the compound. Compound 1, [Ag(tpa)(tfa)]_n, forms a 1D coordination polymer of [Ag(tpa)(tfa)]₂ dimer units linked through bridging tfa counterions. Compound 2, [Ag(tpa)(CH₃CN)(NO₃)]_n, forms a zigzag chain 1D coordination polymer exclusively through Ag−N bonds. In compounds 1 and 2, each tpa ligand is bound to two Ag(I) ions via a 2-py and a 3-py group. Compound 3, [Ag(tpa)(OTf)]_n, forms a ribbonlike 1D coordination polymer, in which each tpa ligand binds to three different silver centers via all three pyridyl groups, and the counterion remains coordinated to the Ag(I) center. Compounds 4, [Ag(tpa)(CH₃CN)]_n(PF₆)_n, and 5, [Ag(tpa)(CH₃CN)]_n (ClO₄)_n, display ribbonlike structures resembling that of 3, except that the counterions are not coordinated. All complexes are luminescent in acetonitrile solution, with emission maxima in the near-UV region (λ_max = 366, 368, 367, 367, and 368 nm for 1−5, respectively). At 77 K, the emission maxima are red-shifted to λ_max = 452, 453, 450, 450, and 454 nm for 1−5, respectively.