Anion Dependent Structures of Luminescent Silver(I) Complexes

Abstract

The reaction of AgX, where X = trifluoroacetate (CF₃CO₂^-, tfa), nitrate (NO₃^-), trifluoromethanesulfonate (triflate,\nCF₃SO₃^-, OTf), hexafluorophosphate (PF₆^-), or perchlorate (ClO₄^-), with 2,2‘,3‘ ‘-tripyridylamine (tpa) yields five\nnovel silver(I) complexes, which have been structurally characterized. The five complexes have the same 1:1\nstoichiometry of Ag/tpa but exhibit different modes of coordination, depending upon the counterion present in the\ncompound. Compound <b>1</b>, [Ag(tpa)(tfa)]<i>_n</i>, forms a 1D coordination polymer of [Ag(tpa)(tfa)]₂ dimer units linked through\nbridging tfa counterions. Compound <b>2</b>, [Ag(tpa)(CH₃CN)(NO₃)]<i>_n</i>, forms a zigzag chain 1D coordination polymer\nexclusively through Ag−N bonds. In compounds <b>1 </b>and <b>2</b>, each tpa ligand is bound to two Ag(I) ions via a 2-py and\na 3-py group. Compound <b>3</b>, [Ag(tpa)(OTf)]<i>_n</i>, forms a ribbonlike 1D coordination polymer, in which each tpa ligand\nbinds to three different silver centers via all three pyridyl groups, and the counterion remains coordinated to the\nAg(I) center. Compounds <b>4</b>, [Ag(tpa)(CH₃CN)]<i>_n</i>(PF₆)<i>_n</i>, and <b>5</b>, [Ag(tpa)(CH₃CN)]<i>_n</i> (ClO₄)<i>_n</i>, display ribbonlike structures\nresembling that of <b>3</b>, except that the counterions are not coordinated. All complexes are luminescent in acetonitrile\nsolution, with emission maxima in the near-UV region (λ_max = 366, 368, 367, 367, and 368 nm for <b>1</b>−<b>5</b>, respectively).\nAt 77 K, the emission maxima are red-shifted to λ_max = 452, 453, 450, 450, and 454 nm for <b>1</b>−<b>5</b>, respectively.