IR spectroscopy of gaseous fluorocarbon ions: the...

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ISCPLTPin honour of Prof Mario Capitelli

IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion

Simonetta Fornarini, Barbara Chiavarino,

Maria Elisa Crestoni

Joel Lemaire, Philippe Maitre

Laboratoire de Chimie Physique, Université Paris-Sud, CNRS, Faculté des Sciences d’ Orsay, Orsay

Dipartimento di Chimica e Tecnologia del Farmaco, Università di Roma “La Sapienza”

02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion

Pagina 2

The structure of C2F5- : two isomers for F-(C2F4) were proposed

K. Hiraoka, N. Mochizuki, A. Wada, H. Okada, T. Ichikawa, D. Asakawa, I. Yazawa, Int. J. Mass Spectrom. 272 (2008) 22.

F-(C2F4)(a) F-(C2F4)(b)

loosely bound tightly bound

Any role for negative hyperconjugation?

A. E. Reed, P. V. R. Schleyer, J. Am. Chem. Soc. 112 (1990) 1434; P. v. R. Schleyer, A. J. Kos, Tetrahedron 39 (1983) 1141

CF3-CF2- CF2=CF2

Pagina 3

Determining the structures of gaseous ions

- Ion spectroscopy

- Ab initio calculations

- Ion-molecule reactions

IRMPD (IR Multiple Photon Dissociation) spectroscopy

Pagina 4

IRMPD spectroscopy: ‘action spectroscopy’

Energy

CLIO free electron laser, pulsed laser at 25 Hz, 500-2500 cm-1, power ca. 1W

Mass spectrum before selection

Mass spectrum after irradiation

m/zMass spectrum after selection but before irradiation

Pagina 5

Ion-molecule reaction of C2F5- with SiF4

Time dependence of the relative ion abundances when selected C2F5- ions are allowed

to react with SF4 at 1.8 × 10-8 mbar in the cell of a FT-ICR mass spectrometer

5 10 15 20Time (s)

C2F5SiF4-

C2F5- + SiF4 SiF5

- + [C2F4] F- transfer

Pagina 6

Ion-molecule reactions of C2F5-

C2F5- + SiF4 SiF5

- + [C2F4]

C2F5NO2

C2F5- + + NO2

C2F5- + OP(OMe)3 C2F5CH3 + (MeO)2PO2

C2F5- + COS [C2F5COS]-

C2F5- + SO2 [C2F5SO2]-

C2F5- + (CH3CO)2CH2 C2F5H + (CH3CO)2CH-

C2F5- + (CH3C(O)OCH3 C2F5H + -CH2C(O) CH3X

F- transfer

addition

nucleophilic substitution

proton transfer

F- -A(SiF4) = 259 kJ/mol

F- -A(SO2) = 183 kJ/mol

F- -A(COS) = 133 kJ/mol

Pagina 7

Candidate structures for C2F5-

1 (0) 2 (141) 3 (194) MP2/cc-pVTZ Relative energies in kJ/mol

4 (195)

1.355 Å

1.368 Å 1.327 Å

1.334 Å

Pagina 8

800 1000 1200 1400

Wavenumber (cm-1)

MP2/cc-pVTZ calculated IR spectra

C2F5- ions probed by IRMPD spectroscopy

800 1000 1200 1400Wavenumber (cm-1)

11191053

asym σCF2

sym σCF2

asym σCF3

σCC-σCF2-σCF3

nhνC2F5

- F- + [C2F4]

asym σCF3 1227 cm-1

C2F5·

asym σCF3 1184 cm-1

Pagina 9

Gas-phase structure of C6X7+/- ions probed by IRMPD spectroscopy

Protonated benzene, C6H7+ C6F7

σ-complex structure ???

energy (cm-1)

C6H7+ π-complex, calculated

C6H7+ σ-complex, calculated

C6H7+ experimental

Jones, Boissel, Chiavarino, Crestoni, Fornarini, Lemaire, Maitre Angew. Chem. Int. Ed. 2003, 42,2057

1200 1400 1600 1800Energy (cm-1)

Pagina 10

B. Chiavarino, M. E. Crestoni, S. Fornarini, F. Lanucara, J. Lemaire, P. Maitre (i)Angew. Chem. Int. Ed. 2007, 46, 1995-1998; (ii) Chem. Eur. J. 2009, 15, 8185-8195; (iii) to be published

Gaseous complexes of negative ions (A-) with TNB

+ A-NO2

[TNB-A]-ESI

- collision induced dissociation experiments at variable energy- IRMPD spectroscopy using the CLIO-FEL beamline- quantum chemical (DFT) calculations

A = Br, I, OH, OCH3, OC2H5, CN

Pagina 11

Anion–arene adducts: C–H hydrogen bonding, anion–π interaction, and carbon bonding motifs

B. P. Hay, V. S. Bryantsev, Chem. Commun. 2008, 2417-2428

C-H hydrogen bonding

Non-covalent anion-π interaction

Weakly covalent σ interaction

Strongly covalent σ interaction

Pagina 12

IRMPD spectrum of TNB-CH3O- complex

Calculated IR spectra (B3LYP/6-311++G(d,p)) Experimental IRMPD

spectrum

Erel = 0

Erel = 101 kJ/mol

800 18001300

1261 1285

B. Chiavarino, M. E. Crestoni, S. Fornarini, F. Lanucara, J. Lemaire, P. Maître, Angew. Chem. Int. Ed. 2007, 46, 1995-1998

Wavenumber (cm-1)

1000 1200 1400 1600 1800

1055 15001594

IRMPD spectrum of TNB-Br- complex

Calculated IR spectra (B3LYP/6-311++G(d,p)) Experimental IRMPD

spectrum

Wavenumber (cm-1)

1000 1200 1400 1600 1800

14301525

1000 1200 1400 1600 1800

16391563

1000 1200 1400 1600 1800

TNB1600

16601080

B. Chiavarino, M. E. Crestoni, S. Fornarini, F. Lanucara, J. Lemaire, P. Maître, D. Scuderi Chem. Eur. J. 2009, 15, 8185-8195

Pagina 13

Pagina 14

Spectroscopic evidence for two types of structural motifs for bare anion-arene interactions

TNB-OH- TNB-OCH3-

TNB-Br- TNB-I-

Weakly covalent σ interaction

Strongly covalent σ interaction

TNB-CN-

Pagina 15

Happy 70th birthday!

Wishing you many more healthful and productive years and thanking you for an

invaluable friendly relationship

My thanks to:

Barbara Chiavarino, Maria Elisa Crestoni, Francesco Lanucara, Joel Lemaire, Philippe

Maître, Debora Scuderi

Jean-Michel Ortega and the CLIO team

The Italian Ministero dell’Università e della Ricerca (PRIN program), Ateneo “La Sapienza”

and the European Commission through the NEST/ADVENTURE program

The kind organizers of ISCPLTP

This audience!

Ion trap MS

CLIO FEL for IRMPD spectroscopy

IRMPD mechanism

IR-MPD mechanism in polyatomic molecules, showing how the energy pumped into a specific vibrational mode is quickly redistributed over the bath of background states by virtue of IVR

ESI source

capillary

laserions

7 T magnet

ion fu

RF hexap

oleRF qu

ole gu

collisi

electr

FT-ICR ce

Schematic of the instrument admitting the IR laser beam in the FT-ICR cell

IR spectroscopy of gaseous fluorocarbon ions: the...

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