Institut für Physikalische Chemie & Elektrochemie, Lehrgebiet A.ppt Zentrum für Festkörperchemie...
19
Institut für Physikalische Chemie & Elektrochemie, Lehrgebiet A <Dateiname>.ppt Zentrum für Festkörperchem ie & Neue Materialien HALOGEN BOND AND INTERNAL MOTIONS: THE LOW-BARRIER CASE OF CF 3 Cl-DIMETHYLETHER. LUCA EVANGELISTI, GANG FENG, QIAN GOU AND WALTHER CAMINATI, Università di Bologna, Italy JENS-UWE GRABOW, Universität Hannover, Germany
-
Upload
bruns-strecker -
Category
Documents
-
view
107 -
download
2
Transcript of Institut für Physikalische Chemie & Elektrochemie, Lehrgebiet A.ppt Zentrum für Festkörperchemie...
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
HALOGEN BOND AND INTERNAL MOTIONS:THE LOW-BARRIER CASE OF
CF3Cl-DIMETHYLETHER.
LUCA EVANGELISTI, GANG FENG, QIAN GOU AND WALTHER CAMINATI, Università di Bologna, Italy
JENS-UWE GRABOW, Universität Hannover, Germany
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Non-covalent Bond Interactions
A) Normal Hydrogen Bond (Strong, ≈ 25 kJ/mol)B) Improper Hydrogen Bond (Weak, << 25 kJ/mol)
C) Anti Hydrogen Bond (Weak, << 25 kJ/mol)
The weak hydrogen bond in structural chemistry and biology, IUCr Monographs on crystallography, Vol. IX (G.R. Desiraju, T. Steiner eds.), Oxford University Press (2001). S. N. Delanoye, W.A. Herrebout, B.J. Van der Veken, J. Am. Chem. Soc. 124 (2002) 11854.
data are available from X-ray diffraction, theoretical calculations, IR absorption in rare gas solutions, and rotationally resolved spectroscopy.
C. G. Cole, A. C. Legon, Chem. Phys. Lett. 396 (2003) 31.
Halogen BondD. Hauchecorne, B. J. van der Veken, A. Moiana, W. Herrebout, Chem. Phys. 374 (2010) 30; D. Hauchecorne, R. Szostak, W. A. Herrebout, B. J. van der Veken. ChemPhysChem 10 (2009) 2105.
A. C. Legon, Angew. Chem. Int. Ed. 38 (1999) 2686; A. C. Legon, Phys. Chem. Chem. Phys. 12 (2010) 7736.
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
•Supersonic Jet ExpansionMolecular Clustersnon-covalent BondingConformational Equilibria
•Molecular DynamicsLarge Amplitude MotionsInternal Rotation
FT-MW spectroscopy of species withnon-convalent halogen bonds (HaB)
Standard ab-initio and DFT calculations: Gaussian or others.
Economy calculations: Distributed polarizability model.
Conformations and potential energy surfaces of molecular adducts.
Effective Hamiltonian fits: Watson, coupled, …
Analysis with obs.-calc. deviations down to a few kHz (< 10-7 cm-1).
Effective potential function fits: flexible model
Inclusion of structural relaxations.
The HaB is competitive and sometimes preferred to the HB.The HaB is often more linear than the HB, with B···X-Y angles ~180°.
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Bologna supersonic jet FT-MW Spectrometer I:
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Plausible Conformations of Dimethylether…Cl-CF3
MP2/6-311++G(d,p): Four configurations of CF3Cl-DME have been found to be stable within 1000 cm-1.
I ∆E = 0 cm-1 [a]
∆E0 = 0 cm-1 [b]
II
107 cm-1 41 cm-1
III
∆E = 715 cm-1
IV
716 cm-1
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
PI group theory Dimethylether…Cl-CF3
2 x CH3 group & CF3 group: C3(1) C3(1)C3(2) = G27
Cs point group symmetry: E,
Molecular symmetry group: G54 (all internal rotations feasible)
H1
Cl
H3H2
C3 axis
C3 E C3 C3²
E (123) (123)² = (132)
A1 1 1 1
E 1 *
1 *
H. C. Longuet-Higgins, Mol. Phys. 6 (1963), 445.J. T. Hougen, J. Chem. Phys. 37 (1962), 1433; J. Chem. Phys. 39 (1963), 358.
C3 group
X1
X2X3
Γ(G54): A1, E1, E2, E3, E4, E5, G1, G2, G3, G4
But no internal rotation splitting observed!
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Another case: PI group theory CH3-F…H-CF3
CH3 group & CF3 group: C3(1)C3(2) = G9
Cs point group symmetry: E,
Molecular symmetry group: G18
H1
Cl
H3H2
C3 axis
C3 E C3 C3²
E (123) (123)² = (132)
A1 1 1 1
E 1 *
1 *
C3 group
X1
X2X3
Γ(G18): A1, E1, E2, E3, E4 Only one internal rotation splitting (A1, E1) observed!
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
CF3-Top Internal Rotation Fine Structure
J,Ka,Kc ← J,Ka,Kc = 31,3←21,2
CH3 top & CF3 top
Only one splitting observed
Effective moment of inertia Iα = 86.0(3) uÅ2 for A1-E1 splitting of CH3F-CHF3
only slightly smaller thanIα = 89.23(2) uÅ2 for isolated CHF3
E1
A1 E1
A1
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Rigid Oxirane-Difluoromethane:Addivity of Planar Moments
Pii = 1/2 (-Iii + Ijj + Ikk) , i,j,k = a,b,c
S. Blanco, J.C. Lopez, A. Lesarri, W. Caminati, J.L. Alonso, ChemPhysChem 5 (2004) 1779.
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
CH3-Top Internal Rotation Inertia Defect
Pbb of the complex should amount to
Pbb(CHF3) + Pbb(CH3F) = 44.62 uÅ2 + 1.55 uÅ2 = 46.17 uÅ2.
Experimental Pbb of the complex isPbb(CHF3
…CH3F) = 44.69 uÅ2, i.e. 1.48 uÅ2 smaller.
Planar moment of inertia Pbb = (h/16π2)(-1/B + 1/A + 1/C)
is related to V3 barrier of internal rotor by:
A00 = Ar + W00(2) F ρa
2
B00 = Br
C00 = Cr+ W00(2) F ρc
2
Experimental Pbb is reproduced for
V3 (CH3) = 0.36 kJ/mol (= 30 cm-1).
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Barriers to Internal Rotation:CH3 and CF3 Tops
V3 (CH3) = 0.36 kJ/mol
V’3 (CF3) = 0.840(5) kJ/mol
MP2/6-311++G(2df,2p): EXPERIMENTAL:
from planar moments Pbb
from A1-E1 splittings
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Internal rotor CF3 CH3
I / u Å2 85.0 3.20
V3 / kJ mol-1 0.840 0.36
s = 4V3/9F 67.92 2.5
AE[*] / MHz 2.6·10-1 1.2·105
CF3 and CH3 Internal Rotors:
Energy Spacing
Barrier & Inertia
Ratio 106
[*]: Energy spacing between A1 and E1 or E2 sublevels.
Weak CH···F Bridges and Internal Dynamics inthe CH3F·CHF3 Molecular Complex**
Walther Caminati,* Juan C. Lòpez, José L. Alonso, and Jens-Uwe Grabow
Angew. Chem. Int. Ed. 2005, 44, 3840-3844
Molecular Complexes VIP
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Dimethylether…Cl-CF3:MP2/6-311++G(d,p) results for most stable conformers
I II III IV
A/MHz 2453 3497 3651 2514
B/MHz 1005 595 601 705
C/MHz 872 570 572 614
μa/D -1.1, -2.1, -2.3, -2.3,
μb/D -0.1, 0.0, 0.0, 0.0,
μc/D 0.8 1.0 0.0 0.0
χaa/MHz 38.3 -71.4 -73.2 36.3
(χbb-χcc)/MHz -95.7 3.0 0.5 -109.6
χab/MHz 2.6 0.1 -2.1 8.8
χac/MHz 0.1 -18.3 -8.0 0.0
χbc/MHz -27.5 -0.0 -0.2 0.0
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Dimethylether…Cl-CF3:Spectrocopic Constants for observed isotopologs
35Cl 37ClA/MHz 11738(8) 11616(11)B/MHz 595.3990(9) 595.367(1)C/MHz 565.8360(7) 565.961(1)χaa/MHz -76.587(3) -60.0(2)(χbb-χcc)/MHz 2.46(4) 0.7(6)DJ/kHz 1.146(4) 1.077(5)DJK/MHz -1.008(3) -0.9906(3)d1/kHz 0.027(1) 0.094(7)HJ/Hz -0.220(1) -0.39(2)h1/Hz -0.080(2) -0.27(3)b/kHz 10.0 10.0Nc 80 61
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Dimethylether…Cl-CF3: Planar Moment
Pbb of the complex should amount to
Pbb(CHF3)+Pbb(H3COCH3)=44.62 uÅ2+45.00 uÅ2=89.62 uÅ2
Experimental Pbb of the complex isPbb(CHF3
…H3COCH3) = 43.701 uÅ2, i.e. 45.919 uÅ2 smaller.
Planar moment of inertia Pbb = (h/16π2)(-1/B + 1/A + 1/C)
is related to V3 barrier of internal rotor by:
A00 = Ar + W00(2) F ρa
2 = Ar + W00(2) F ρa
2
B00 = Br + W00(2) F ρb
2 = Br
C00 = Cr + W00(2) F ρc
2 = Cr
Experimental Pbb is reproduced for
V3 (CF3) = ~0 kJ/mol (VERY SMALL).
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Dimethylether…Cl-CF3 Complex:Force Constant and Dissociation Energy
OClC halogen bond (HaB)
ks = 1.3 Nm-1
ED = 2.7 kJ·mol-1
(similar to weak hydrogen bond (HB) << 25 kJ/mol)
DJ = DJ(eff) – [-1/2 (ρb4 + ρc
4) W00(4) F] (small contribution)
ks = 16π4 (μ RCM)2 [4B4 + 4C4 - (B-C)2 (B+C)2] / (h DJ)ED(Lennard-Jones) = 1/72 ks RCM
2
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
Coaxial oriented Beam-Resonator Arrangement (COBRA)
Fabry-Perot resonator
resonatortuning
FT
FID
Impulse
polarization pulse:
coherence between
rotating molecular dipoles
oscillating macroscopic
dipole moment:
electromagnetic field at frequencies
of molecular transitions
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
In-Phase/Quadrature-Phase Modulation Passage-Acquired Coherence Technique (IMPACT) FT-MW
polarization chirp:
superposition of multiple coherence
Between rotating molecular dipoles
superposition of oscillating macroscopic
dipole moments:
electromagnetic field at frequencies
of participating molecular transitions
(LASER-ablation)source planar
reflector
parabolicreflectors
double-ridgehorn
chirp
t
FT
FID
linewidth < 10kHz
Doppler doublets
Ins
titu
t fü
r P
hy
sik
ali
sc
he
Ch
em
ie &
Ele
ktr
oc
he
mie
, L
eh
rge
bie
t A
<Dateiname>.ppt
Zentrum für Festkörperchemie
&Neue
Materialien
AcknowledgementAcknowledgement
Deutsche Forschungsgemeinschaft (DFG)
Land Niedersachsen
Università di Bologna
Minister of Education, Italy
