1. Preference for Top- vs. Side-binding in Fluorinated Ethylene…CO2 Complexes
Ashley M. Anderton, Cori L. Christenholz, Rachel E. Dorris, Rebecca A. Peebles,
Sean A. Peebles
Department of Chemistry, Eastern Illinois University, 600 Lincoln Ave., Charleston, IL 61920

2. ? C-H…O Interactions Previous CO2 (and OCS) complexes
Serafin, et al., J. Phys. Chem. A, 110, (2006),
Serafin, et al., J. Phys. Chem. A, 112, (2008),
Serafin, et al., J. Phys. Chem. A, 112, (2008), 1473.
Serafin, et al., J. Mol. Spec., 250, (2008), 1.
Thomas, et al., J. Mol. Spec., 289, (2013), 65. ?

3. C-H…X and C-H…p InteractionsF F F F F F F F
Varying degree of fluorination
Side vs. top binding F F
FE…CH2F2: C. L. Christenholz, et al., J. Phys. Chem. A 118 (2014) 1610.
DFE…CH2F2: Y. Tatamitani, et al., J. Mol. Spectrosc. 242 (2007) 150.
FE…CHF3: L. F. Elmuti, et al., work in progress.

4. Previous Work Leung and Marshall “top” vs. “side” binding
Variation with degree and location of fluorination F F F F
FE…HCCH: G. C. Cole, et al., Chem. Phys. Lett. 369 (2003) 31.
DFE…HCCH: H. O. Leung, et al., J. Chem. Phys. 125 (2006)
TFE…HCCH: H. O. Leung, et al., J. Chem. Phys. 128 (2008)

5. Ab Initio Calculations
MP2/ G(2d,2p)

6. Ab Initio Predictions Further calculations for FE…CO2: “Stacked”
Structures DE / cm-1
“Side”
“Top” FE 42 55
DFE 46
TFE -- 54
Further calculations for FE…CO2:
DE (ZPE+BSSE) / cm-1 FE 1 7
a For FE, DE column values are ZPE corrected and DE(ZPE) values are ZPE and BSSE corrected.

7. Experimental Spectra scanned on 480 MHz CP-FTMW spectrometer
~1% of each component
He/Ne carrier at ~2.5 atm
FE: Scanned 6 – 19 GHz
5000 FIDs/step; 4 FIDs/nozzle pulse
DFE: Scanned 6 – 18.5 GHz
TFE: “Old fashioned” method
500 shots at selected frequencies
Recently scanned: 2000 FIDs/step; 6 FIDs/nozzle pulse

8. FE…CO2
Two isomers!

9. DFE…CO2

10. TFE…CO2 Only side binding observed
Stacked structure would not converge
Performed additional scan to look for top structure…
Also, possible Ne or H2O complex

11. Spectroscopic Constants
Normal
Ab Initio
13CO2
13CH
13CF
C18O2 FE
A / MHz
(17)
9550
(32)
Side
B / MHz
(6)
1372
(6)
C / MHz
(4)
1200
(6)
(16)
6668
(29)
(19)
(20)
Top
(15)
1661
(6)
(8)
(8)
(13)
1330
(7)
(8)
(8)
DFE
(9)
5672
(5)
(31)
(31)
(23)
(24)
1130
(4)
(5)
(5)
(5)
(4)
942
(32)
(4)
(4)
(5)
TFE
(21)
5285
(33) a
(16) b
(3)
(3)
703
(18)
(8)
(11)
(2)
621
(7)
(2)
(8)
Required table of numbers
Isotope info?
a C18O16O (18O near F)
b C16O18O (18O near H)

12. Comparison… 2.900(4) Å 2.935(10) Å 2.680(11) Å 2.58(10) Å 2.954(22) Å
2.695(22) Å
2.916(12) Å
2.725(12) Å

13. Dipole Moment and Binding Energyma mb
mtotal
Expt.
Proj.
Ab Init.
FE Side
1.083(4)
0.92
1.00
1.001(3)
1.15
1.09
1.475(5)
1.47
1.48
FE Top
1.435(2)
1.34
1.45
0.567(3)
0.60
0.58
1.543(3)
1.56
DFE Top
0.064(18)
0.04
0.03
1.345(2)
1.37
1.30
1.409(6)
TFE Side
0.246(28)
0.35
0.36
1.230(10)
1.26
1.18
1.254(15)
1.23
Induction effects mainly less than ~0.1 D
ks / N m
EB / kJ mol-1
n / cm-1
FE Side
5.0(1)
5.8(2)
62(1)
FE Top
6.2(1)
6.1(1)
68(1)
DFE Top
4.5(1)
5.8(1)
54(1)
TFE Side
4.1(1)
7.2(1)
49(1)

14. Why Side vs. Top Binding? Look at simple electrostatics
Dipole and quadrupole direction in monomers

15. Conclusions Structures driven by weak CH…O interactions
Simple quadrupole-dipole and quadrupole-quadrupole interactions seem important
MP2 calculations
Excellent rotational constant predictions
Energies need closer look…

16. Acknowledgements Cori, Rachel, Ashley
National Science Foundation, RUI
EIU Sidney Steele Fellowship (AMA – Summer 2013)
Other group members past and present…
Lena, Anu, Sarah, Bailey, Nate
Bailey
Rachel
Ashley
Anu
Sarah

17. Ab Initio Predictions Focus just on energies “Above” Structures “Side”
“Top”
DE / cm-1
DE (ZPE) / cm-1
FE a 42 1 55 7
DFE -- 46
TFE 54
a For FE, DE column values are ZPE corrected and DE(ZPE) values are ZPE and BSSE corrected.

18. Ab Initio Predictions “Above” Structures “Side” “Top”
Rot. Const. / MHz
m / D FE
5231
1910
1742
0.67
0.42
1.30
9550
1372
1200
1.00
1.09
0.00
6668
1661
1330
1.45
0.58
DFE
4105
1501
1360
0.12
0.99
0.83 --
5672
1130
942
0.03
TFE
5285
703
621
0.36
1.18
3546
882
706
1.21
0.64

19. 1 2 3 4 5 6 7 9 8
2.680(11) Å
119.8(4)°
90.06()°
137.1(4)°
130.74()°
2.900(4) Å a b
2.935(10) Å
2.58(10) Å
110.5(10)°
96.5(10)°
121.3(10)°
114.7(10)°