title: Different nature of the interactions between anions and HAT(CN)6: from reversible anion-π complexes to irreversible electron-transfer processes (HAT(CN)6 = 1,4,5,8,9,12-hexaazatriphenylene).
abstract: We report experimental evidence indicating that the nature of the interaction established between HAT(CN)(6), a well-known strong electron acceptor aromatic compound, with mono- or polyatomic anions switches from the almost exclusive formation of reversible anion-π complexes, featuring a markedly charge transfer (CT) or formal electron-transfer (ET) character, to the quantitative and irreversible net production of the anion radical [HAT(CN)(6)](•-) and the dianion [HAT(CN)(6)](2-) species. The preferred mode of interaction is dictated by the electron donor abilities of the interacting anion. Thus, weaker Lewis basic anions such as Br(-) or I(-) are prone to form mainly anion-π complexes. On the contrary, stronger Lewis basic F(-) or (-)OH anions display a net ET process. The ET process can be either thermal or photoinduced depending on the HOMO/LUMO energy difference between the electron donor (anion) and the electron acceptor (HAT(CN)(6)). These ET processes possibly involve the intermediacy of anion-π complexes having strong ET character and producing an ion-pair radical complex. We hypothesize that the irreversible dissociation of the pair of radicals forming the solvent-caged complex is caused by the reduced stability (high reactivity) of the radical resulting from the anion.
authors: Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007 Tarragona, Spain.
authors: Gemma
authors: G
authors: Aragay
authors: Antonio
authors: A
authors: Frontera
authors: Vega
authors: V
authors: Lloveras
authors: José
authors: J
authors: Vidal-Gancedo
authors: Pablo
authors: P
authors: Ballester
mesh_terms: D000838:Anions; D001372:Aza Compounds / Q000737:chemistry*; D002911:Chrysenes / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D008958:Models, Molecular; D009570:Nitriles / Q000737:chemistry*; D011810:Quinoxalines / Q000737:chemistry*
chemical_list: C506868:1,4,5,8,9,12-hexaazatriphenylene; C555119:1,4,5,8,9,12-hexaazatriphenylene-hexacarbonitrile; D000838:Anions; D001372:Aza Compounds; D002911:Chrysenes; D009570:Nitriles; D011810:Quinoxalines