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
F-
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
Pagina 3
Determining the structures of gaseous ions
- Ion spectroscopy
- Ab initio calculations
- Ion-molecule reactions
IRMPD (IR Multiple Photon Dissociation) spectroscopy
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
Pagina 4
IRMPD spectroscopy: ‘action spectroscopy’
Energy
IRMPD
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/z
m/zMass spectrum after selection but before irradiation
m/z
nhν
+
IVR
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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
25
50
75
100
5 10 15 20Time (s)
I (%
)
C2F5-
SiF5-
C2F5SiF4-
C2F5- + SiF4 SiF5
- + [C2F4] F- transfer
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
Pagina 7
Candidate structures for C2F5-
1 (0) 2 (141) 3 (194) MP2/cc-pVTZ Relative energies in kJ/mol
(224)
+ F-
4 (195)
1.355 Å
1.368 Å 1.327 Å
1.334 Å
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
Pagina 8
1
2
3
4
1
2
800 1000 1200 1400
Wavenumber (cm-1)
exp
R
MP2/cc-pVTZ calculated IR spectra
C2F5- ions probed by IRMPD spectroscopy
800 1000 1200 1400Wavenumber (cm-1)
1208
819
11191053
908
asym σCF2
sym σCF2
asym σCF3
asym σCF3
σCC-σCF2-σCF3
nhνC2F5
- F- + [C2F4]
asym σCF3 1227 cm-1
C2F5·
asym σCF3 1184 cm-1
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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
+ H H
+ H0
1
2
1200 1400 1600 1800Energy (cm-1)
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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
NO2
O2N
TNB
[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
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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
800 18001300
1261 1285
1378
B. Chiavarino, M. E. Crestoni, S. Fornarini, F. Lanucara, J. Lemaire, P. Maître, Angew. Chem. Int. Ed. 2007, 46, 1995-1998
Wavenumber (cm-1)
R
0
1
2
1000 1200 1400 1600 1800
1055 15001594
1253
IRMPD spectrum of TNB-Br- complex
Calculated IR spectra (B3LYP/6-311++G(d,p)) Experimental IRMPD
spectrum
Wavenumber (cm-1)
0
0,6
1,2
1000 1200 1400 1600 1800
1060
1330
14301525
1600
R
1000 1200 1400 1600 1800
1077
1318
16391563
1000 1200 1400 1600 1800
TNB1600
1367
16601080
1474
B. Chiavarino, M. E. Crestoni, S. Fornarini, F. Lanucara, J. Lemaire, P. Maître, D. Scuderi Chem. Eur. J. 2009, 15, 8185-8195
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
Pagina 13
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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-
02/07/11IR spectroscopy of gaseous fluorocarbon ions: the perfluoroethyl anion
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
nnels
RF hexap
oleRF qu
adrup
ole gu
ide
collisi
on ce
lltra
nsfer
electr
odes
FT-ICR ce
ll
Schematic of the instrument admitting the IR laser beam in the FT-ICR cell