1. The Effect of Protic Acid Identity on the Structures of Complexes with Vinyl Chloride: Fourier Transform Microwave Spectroscopy and Molecular Structure of the Vinyl Chloride-Hydrogen Chloride Complex
Joseph P. Messinger, Helen O. Leung, Mark D. Marshall
Chemistry Department, Amherst College
Amherst, Massachusetts

2. Background: Binding Conformations
19.8 (3)°
2.02 (4) Å
41.6 (51)°
2.59 (1) Å
2.319 (6) Å
2.752 (4) Å
Leung, H. O.; Marshall, M. D. J. Chem. Phys. 126, 2007.
Leung, H. O.; Marshall, M. D. 67th ISMS, TH01, 2012.

3. Background: Acid Substitution
36.5 (2)°
18.3 (1)°
18.7 (15)°
1.892 (14) Å
2.123 (1) Å
2.441 (4) Å
Cole, G. C.; Legon, A. C. Chem. Phys. Lett. 400, 2004.
Kisiel, Z.; Fowler, P. W.; Legon, A. C. J. Chem. Phys. 93, 1990.
Cole, G. C.; Legon, A. C. Chem. Phys. Lett. 369, 2003.

4. Background: Chloroethylene
19.8 (3)°
Leung, H.O.; Marshall, M. D.; Feng, F. J. Phys. Chem. A 117, 2013.
2.59 (1) Å
2.319 (6) Å
3.01 (1) Å
58.5 (5)°
2.939 (4) Å
Leung, H. O.; Marshall, M. D. 67th ISMS, TH01, 2012.

5. Non-Planar Theoretical Calculations
Gaussian 09
MP2/ G(2d,2p)

6. Minima Structures Energy (cm-1) 35.05 52.07
35.05
52.07
A = MHz μa = 1.85 Debye
B = MHz μb = 1.04 Debye
C = MHz μc = 0.32 Debye

7. Experimental Methods
Chirped pulse Fourier transform microwave spectrometer: GHz Balle-Flygare Fourier transform microwave spectrometer: GHz Mixture was 1% vinyl chloride and 1% HCl in argon
Photo courtesy of Jessica Mueller, Amherst College
Photo courtesy of Aaron Bozzi, Amherst College

8. Experimental Results

9. Experimental Results C2H335Cl-H35Cl C2H337Cl-H35Cl C2H335Cl-H37Cl
C2H335Cl-H35Cl
C2H337Cl-H35Cl
C2H335Cl-H37Cl
C2H337Cl-H37Cl
A (MHz)
(24)
(70)
(74)
(14)
B (MHz)
(12)
(15)
(13)
(17)
C (MHz)
(11)
(98)
(10)
(13)
Highest J 6 4
Highest Ka 2 1
Number of transitions 26 10 12 8
Number of a-type transitions 21 7 9
Number of b-type transitions 5 3
RMS (MHz)
3.154
1.054
1.127
1.302

10. Experimental Constants Theoretical Constants
Experimental Results
C2H335Cl-H35Cl
A (MHz)
(24)
B (MHz)
(12)
C (MHz)
(11)
Highest J 6
Highest Ka 2
Number of transitions 26
Number of a-type transitions 21
Number of b-type transitions 5
RMS (MHz)
3.154
Experimental Constants
Theoretical Constants
A (MHz)
(75)
B (MHz)
(36)
C (MHz)
(34)
Inertial Defect
= amu·Å2

11. Experimental Results: Doubling

12. Ground and Excited States
Ground Tunneling State
Excited Tunneling State
A (MHz)
(24)
5831 (31)
B (MHz)
(12)
(40)
C (MHz)
(11)
(64)
Number of transitions 26 7
Number of a-type transitions 21
Number of b-type transitions 5
RMS (MHz)
3.154
1.488

13. Tunneling Calculations
Gaussian 09
MP2/ G(2d,2p)

14. Structure Determination
Kraitchman Substitution
C2H3Cl
HCl
|a|
(11)
(63)
|b|
(16)
0.302i (50)
|c|
0.086i (17)
0.113i (13)
RMS = amu·Å2

15. Vinyl Chloride Complexes

16. Discussion Explanation for non-planar binding conformation:
Dispersion forces: Ar-haloethylene complexes
Electrostatic: Cl has different electron distribution than F
Steric effects
Vinyl Chloride
Vinyl Fluoride
64.8°

17. Conclusions
- First non-planar haloetheylene-protic acid complex found - Importance of acid identity in chloroethylene complexes - Role of dispersion, electrostatics and sterics. Future Work - Hyperfine structure - More substituted chloroethylenes

18. Acknowledgements