title: Interactions in the ionic liquid [EMIM][FAP]: a coupled experimental and computational analysis.
abstract: Gas-phase electronic and structural properties of the room temperature ionic liquid 1-ethyl-3-methylimidazolium tris(perfluoroethyl)trifluorophosphate ([EMIM][FAP]) were studied using density functional theory, and confirmed with results from infrared spectroscopy. A conformational analysis allowed the identification of several plausible conformers of the ion pairs. For the detected conformers, the infrared spectra were predicted and their thermodynamic properties were evaluated. The topology of the electronic density of the most stable conformers of [EMIM][FAP] ion pairs were characterised using the quantum theory of atoms in molecules. A number of possible hydrogen bonds between the cations and anions of the ionic liquid were identified. Excellent correspondence was found between the predicted spectra of gas-phase [EMIM][FAP] conformers and the experimental infrared spectrum, which in turn allowed a clear attribution of the vibration modes of [EMIM][FAP]. Finally, the contribution of the various conformers of both isomers of the [FAP](-) anion to the ionic liquid macro-properties is shown.
authors.affiliation: CIQ(UP), Faculdade de Ciências da Universidade do Porto, Departamento de Química e Bioquímica, Rua do Campo Alegre, 4169-007 Porto, Portugal. voroshylova.iuliia@fc.up.pt cmpereir@fc.up.pt and LAQV@REQUIMTE, Faculdade de Ciências, Universidade do Porto, Departamento de Química e Bioquímica, Rua do Campo Alegre, 4169-007 Porto, Portugal. ncordeir@fc.up.pt.
authors.forename: Iuliia V
authors.initials: IV
authors.lastname: Voroshylova
authors.affiliation: LAQV@REQUIMTE, Faculdade de Ciências, Universidade do Porto, Departamento de Química e Bioquímica, Rua do Campo Alegre, 4169-007 Porto, Portugal. ncordeir@fc.up.pt.
authors.forename: Filipe
authors.initials: F
authors.lastname: Teixeira
authors.affiliation: CIQ(UP), Faculdade de Ciências da Universidade do Porto, Departamento de Química e Bioquímica, Rua do Campo Alegre, 4169-007 Porto, Portugal. voroshylova.iuliia@fc.up.pt cmpereir@fc.up.pt.
authors.forename: Renata
authors.initials: R
authors.lastname: Costa
authors.affiliation: CIQ(UP), Faculdade de Ciências da Universidade do Porto, Departamento de Química e Bioquímica, Rua do Campo Alegre, 4169-007 Porto, Portugal. voroshylova.iuliia@fc.up.pt cmpereir@fc.up.pt.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Pereira
authors.affiliation: LAQV@REQUIMTE, Faculdade de Ciências, Universidade do Porto, Departamento de Química e Bioquímica, Rua do Campo Alegre, 4169-007 Porto, Portugal. ncordeir@fc.up.pt.
authors.forename: M Natália D S
authors.initials: MN
authors.lastname: Cordeiro