1. Department of Chemistry
Taking the next step with halogenated olefins: Microwave spectroscopy and molecular structures of tetrafluoro- and chloro-trifluoro propenes and their complexes with the argon atom
Mark D. Marshall, Helen O. Leung, Miles Wronkovich, Megan Tracy, Laboni Hoque, Allison Randy-Cofie, and Alina Dao
Department of Chemistry
Amherst College
Supported by the National Science Foundation

2. Intermolecular interactions: fluoroethylenes-protic acids
2.441(4) Å
3.159 Å
122.6(4)o
36.4(2)o
Cole & Legon, Chem. Phys. Lett. 369, 31 (2003).
2.123(1) Å
3.162 Å
123.7(1)o
18.3(1)o
Kisiel, Fowler & Legon, J. Chem. Phys. 93, 3054 (1990).
1.89(1) Å
2.734 Å
121.4o
19(2)o
Cole & Legon, Chem. Phys. Lett. 400, 419 (2004).
The vinyl fluorideHX complexes are planar and adopt the same structural motif. There are two interactions: a H-bond donated by HX, and a secondary interaction between the nucleophilic portion of HX and an H atom cis to F.
As the acid strength decreases, the H bond becomes longer and less linear.
The CF---H angle for each complex indicates that the electron density of F that interacts with the acid is ~120o from the CF bond.

3. Significant differences for chloroethylenes
2.319(6) Å
2.59(1) Å
19.8(3)o
102.4(2)o
vinyl chlorideHF
58.5(5)o
88.7(2)o
3.01(1) Å
2.939(4) Å
vinyl chlorideHCCH
100.0(8)o
39(2)o
2.6810(2) Å
vinyl chlorideHCl
Unlike vinyl fluorideHX, the manner of binding for vinyl chlorideHX depends on the identity of the acid partner.
The "top" binding configuration of the HF complex is less strained than a "side" binding structure.
The "side" binding configuration of the HCCH complex allows it to interact with the most electropositive H atom in vinyl chloride.
The nonplanar HCl complex is likely a result of dispersion interactions that arise between Cl in HCl and the electron density in vinyl chloride.

4. Chlorofluoroethylene-HCCH complexes
Same binding mode as vinyl fluoride-HCCH
HCCH prefers to bind to F
Same binding mode as vinyl chloride-HCCH
HCCH prefers to bind to Cl
First complex observed where an acid binds to Cl, instead of F, in a substituted ethylene

5. Extend to halopropenes by substituting –CF3 group
Vinyl fluoride
2,3,3,3-tetrafluoropropene

6. Extend to halopropenes by substituting –CF3 group
Vinyl chloride
2-chloro-3,3,3-trifluoropropene

7. Extend to halopropenes by substituting –CF3 group
Vinyl chloride
(Z)-1-chloro-3,3,3-trifluoropropene

8. Extend to halopropenes by substituting –CF3 group
Vinyl chloride
(E)-1-chloro-3,3,3-trifluoropropene

9. First step: Characterize monomer spectra and structures

10. Experimental methods
Chirped pulse Fourier transform microwave spectrometer: GHz
Less abundant isotopologues studied as necessary in Balle- Flygare instrument
1% halopropene in argon is expanded through two pulsed valves with 0.8 mm nozzle
Spectra obtained as 4 GHz portions, 20 W power, 4 s chirp
Ten 10-s FIDs per gas pulse
>400,000 FIDs averaged
200 kHz FWHM
Spectra analyzed using Kisiel’s AABS package in conjunction with Pickett’s SPFIT/SPCAT
2,3,3,3-tetrafluoropropene monomer used original Amherst CP-FTMW and somewhat different conditions
Photo courtesy of Jessica Mueller, Amherst College

11. 2,3,3,3-tetrafluropropene
Marshall, Leung, Scheetz, Thaler, and Muenter, JMS, 266, 37 (2011)
CF3CFCH2
CF3CF13CH2
CF313CFCH2
13CF3CFCH2
A / MHz
(50)
(17)
(15)
(12)
B / MHz
(39)
(97)
(91)
(65)
C / MHz
(38)
(93)
(97)
(69)
J / 10-3 MHz
0.2570(86)
0.302(29)
0.249(33)
0.341(23)
JK / 10-3 MHz
1.0862(37)
1.341(77)
1.04(10)
0.988(82)
K / 10-3 MHz
0.8494(89)
0.8494a
J / 10-3 MHz
(42) a
K / 10-3 MHz
2.5308(36)
2.5308a
Highest J 12 5 4
Highest Ka 6 3
rms / kHz
7.44
7.37
5.23
Tune-up molecule for original Amherst CP- FTMW spectrometer
Two 6 GHz portions
5 W power
50,000 FIDs
Helium carrier gas
Four isotopologues
Ab initio anharmonic α’s used to get semi-experimental re structure
aFixed at the value appropriate to the most abundant isotopologue.

12. 2,3,3,3-tetrafluropropene – r0 structure
C1C2 / Å
1.3215a
C2C3 / Å
1.5029b
C1H1 / Å
1.0766c
C1H2 / Å
1.0747c
C2F1 / Å
(55)
C3F2 / Å
(62)d
C3F3 / Å
(62)d
C3F4 / Å
H1C1C2 / o c
H2C1C2 / o c
F1C2C1 / o c
C3C2C1 / o
126.84(13)
F2C3C2 / o
(22)
F3C3C2 / o c
F4C3C2 / o
F3C3C2C1 / o c
F4C3C2C1 / o
 c
No evidence of internal rotation of –CF3 group
Leung, Marshall, Wronkovich, JMS, Caminati Issue, Part 2.
aFixed to the bond length determined by the Kraitchman analysis
bCalculated from the Kraitchman coordinates by assuming that C3 lies on the a axis
cFixed to ab initio value.
dThe C3–F3 and C3–F4 bonds are assumed to have the same length, which in turn is fixed to be Å longer than that for C3–F2, as suggested by ab initio results.

13. 2-chloro-3,3,3-trifluoropropene
Rich a/b-type spectrum
35Cl/ 37Cl isotopologues
Cl nuclear quadupole coupling hyperfine
All provide additional structural information

14. 2-chloro-3,3,3-trifluoropropene broadband spectra (MHz)
CF3C35ClCH2
CF3C37ClCH2
CF3C35Cl13CH2
CF313C35ClCH2
13CF3C35ClCH2 A
(17)
(24)
(11)
(70)
(10) B
(98)
(13)
(59)
(66)
(55) C
(81)
(13)
(42)
(58)
(83)
ΔJ/10-3
0.1748(11)
0.1681(25)
0.1468(69)
0.139(12)
0.1750(90)
ΔJK/10-3
0.6728(34)
0.6600(56)
0.668(28)
0.865(47)
0.586(31)
ΔK/10-3
(46)
-0.420(11)
-0.31(10)
-0.729(66)
-0.304(57)
δJ/10-3
(28)
(46)
0.0404(36)
0.0306(42)
0.0572(49)
δK/10-3
(28)
-1.310(10)
-1.352(43)
-1.695(85)
-1.287(96)
χaa (Cl)
(33)
(35)
(15)
(15)
(22)
χbb (Cl)
(34)
0.5818(39)
-1.571(12)
-0.808(13)
-0.617(17)
χcc (Cl)
(31)
(33)
34.566(13)
34.553(13)
34.570(14)
|χab|(Cl)
54.88(36)
42.70(59)
53.07(85)
55.5(17)
51.5(24)
rms/kHz
4.28
3.38
7.04
6.28
7.13
J range
1-12
1-10
2-7
2-10
Ka range
0-6
0-5
0-4
Pcc / u Å2
44.24

15. 2-chloro-3,3,3-trifluoropropene narrowband spectra (MHz)
CF3C35Cl13CH2
CF313C35ClCH2
13CF3C35ClCH2
CF3C37Cl13CH2
CF313C37ClCH2
13CF3C37ClCH2 A
(34)
(30)
(26)
(41)
(32)
(70) B
(16)
(27)
(30)
(36)
(19)
(40) C
(13)
(21)
(22)
(19)
(12)
(30)
ΔJ/10-3
0.1684(21)
0.1683(37)
0.1844(40)
0.1600(51)
0.1720(33)
0.1710(59)
ΔJK/10-3
0.6600(85)
0.708(16)
0.640(12)
0.669(21)
0.650(18)
0.671(31)
ΔK/10-3
-0.383(33)
-0.490(27)
-0.442(12)
(26)
-0.420*
-0.460(40)
δJ/10-3
0.0438(11)
0.0390(18)
0.0453(21)
0.0387(26)
0.0411(13)
0.0407(24)
δK/10-3
-1.375(14)
-1.441(35)
-1.295(35)
-1.520(46)
-1.340(44)
-1.41(10)
χaa (Cl)
(43)
(67)
(66)
(59)
(10)
(14)
χbb (Cl)
(37)
(59)
(51)
(47)
(38)
(65)
χcc (Cl)
(37)
(61)
(50)
(58)
(82)
27.220(67)
|χab|(Cl)
54.91(24)
53.40(82)
52.10(82)
47.84(39)
43.80(89)
42.3(25)
rms/kHz
2.494
3.017
2.938
2.295
0.822
1.832
J range
1-7
1-9
1-6
Ka range
0-3
0-4
0-5
Pcc / u Å2
44.24

16. 2-chloro-3,3,3-trifluoropropene structure
No evidence of internal rotation of –CF3 group
Kisiel’s STRFIT used to fit A, B, C of 8 isotopologues to 7 structural parameters
Numbers in brackets fixed at ab initio values
rms = u Å2 and well-behaved correlations

17. (Z)-1-chloro-3,3,3-trifluoropropene broadband spectra (MHz)
CH35ClCHCF3
CH37ClCHCF3
13CH35ClCHCF3
CH35Cl13CHCF3
CH35ClCH13CF3 A
(19)
(31)
(11)
(11)
(97) B
(71)
(96)
(83)
(69)
(51) C
(70)
(81)
(90)
(81)
(60)
ΔJ/10-3
(44)
(58)
0.2932(53)
0.2901(49)
0.2839(55)
ΔJK/10-3
4.4062(17)
4.2763(20)
4.094(29)
4.307(26)
4.412(19)
ΔK/10-3
-3.727(13)
-3.639(30)
-4.04(14)
-3.59(11)
-3.85(10)
δJ/10-3
(61)
(86)
0.0326(28)
(77)
0.0260(11)
δK/10-3
(62)
-3.355(16)
-2.67(36)
-2.53(36)
-3.29(19)
χaa (Cl)
8.7789(27)
6.4971(33)
9.352(13)
8.722(13)
8.767(13)
χbb (Cl)
(26)
(30)
(10)
(11)
(99)
χcc (Cl)
(25)
(31)
(26)
30.390(10)
30.37(11)
|χab (Cl)|
51.937(38)
41.30(62)
52.68(60)
51.08(70)
53.15(58)
J range
0-17
0-15
0-8
0-11
Ka range
0-6
0-5
0-3
rms / kHz
4.97
5.56
8.40
8.31
7.46
Pcc / u Å2
44.35

18. (Z)-1-chloro-3,3,3-trifluoropropene structure
Determined by fixed C–F bond length and Pcc
Kisiel’s STRFIT used to fit A, B, C of 5 isotopologues to 5 structural parameters
Numbers in brackets fixed at ab initio values
rms = u Å2 and well- behaved correlations
(35)°
127.4(20)°
125.7(15)°
1.530(28) Å
1.682(21) Å
No evidence of internal rotation of –CF3 group
1.250(53) Å

19. (E)-1-chloro-3,3,3-trifluoropropene broadband spectra (MHz)
CH35ClCHCF3
CH37ClCHCF3 A
(72)
5182.3(37) B
(50)
(31) C
(50)
(31)
ΔJ / 10-3
0.0392(28)
0.0708(14)
ΔJK / 10-3
1.444(26)
1.161(11)
ΔK / 10-3
[ 0.]*
δJ / 10-3
[ ]*
0.0133(30)
δK / 10-3
49.97(27)
χaa
(15)
(27)
χbb
31.695(19)
24.795(40)
χcc
31.458(20)
25.035(40)
|χab|
[ 28.52]*
13.0(12)
J range
3 - 9
4 - 9
Ka range
0 - 5
0 - 6
rms / kHz
15.6
16.7
Pcc
44.29
45.31
Only a-type transitions observed
μb is very small
13C isotope shifts small
Stay tuned for structure…
*held fixed at ab initio values

20. Ar-2,3,3,3-tetrafluropropene (MHz)
Ar−CF3CFCH2
Ar−CF3CF13CH2
Ar−CF313CFCH2
Ar−13CF3CFCH2 A
(36)
(15)
(17)
(15) B
(15)
(10)
(10)
(97) C
(14)
(97)
(92)
(90)
J / 10-3
(68)
(57)
(58)
(54)
JK / 10-3
4.5457(23)
4.6200(40)
4.5638(40)
4.4487(37)
K / 10-3
4.8754(97)
4.3075(80)
4.8557(88)
5.0374(77)
J / 10-3
(22)
(23)
(23)
(22)
K / 10-3
0.506(13)
0.684(36)
0.543(36)
0.490(35)
J range
1 – 16
1 – 11
Ka range
0 – 7
0 – 4
rms / kHz
11.23
1.48
1.55
Spectra obtained on Balle-Flygare FTMW
Leung, Marshall, Wronkovich, JMS, Caminati Issue, Part 2.

21. Ar-2-chloro-3,3,3-trifluoropropene (MHz)
(89) Å
3.7234(11) Å
3.9736(29) Å
3.5441(18) Å
Ar-CF3C35ClCH2
Ar-CF3C37ClCH2 A
(20)
(13) B
(13)
(12) C
(13)
(14)
ΔJ/10-3
1.5476(10)
1.3414(85)
ΔJK/10-3
2.0533(38)
2.146(26)
ΔK/10-3
1.3817(39)
1.650*
δJ/10-3
(50)
0.5822*
δK/10-3
2.367(10)
1.427*
χaa (Cl)
41.138(13)
33.13(14)
χbb (Cl)
(28)
-7.785(21)
|χab| (Cl)
16.41*
38.7(98)
|χac| (Cl)
13.67*
10.51*
|χbc| (Cl)
48.36*
38.50(81)
rms/kHz
7.64
23.4
Kisiel’s STRFIT used to fit A, B, C of 2 isotopologues to r, θ, φ of Ar.
Halopropene fixed at monomer values
rms = u Å2 and reasonable correlations
Ar almost directly above C2, shaded toward Cl
EVAL used to calculate 4 closest heavy atom contacts
*held fixed at ab initio values

22. Ar-(Z)-1-chloro-3,3,3-trifluoropropene (MHz)
Ar-CH35ClCHCF3
Ar-CH37ClCHCF3 A
(36)
(53) B
(18)
(36) C
(14)
(52)
ΔJ/10-3
1.5874(13)
1.5780(31)
ΔJK/10-3
(73)
-2.815(14)
ΔK/10-3
8.589(11)
8.564(21)
δJ/10-3
(50)
(95)
δK/10-3
1.5081(64)
1.483(12)
χaa (Cl)
28.038(12)
22.001(25)
χbb (Cl)
9.581(10)
7.196(17)
χcc (Cl)
(86)
(14)
|χab|(Cl)
-18.2(26)
-8.8(71)
|χac|(Cl)
24.31(89)
23.4(34)
|χbc|(Cl)
46.718(63)
37.0(10)
J range
2-14
2-12
Ka range
0-6
rms / kHz
8.726
7.739
3.7622(65) Å
3.9378(22) Å
3.6472(64) Å
3.4630(55) Å
Kisiel’s STRFIT used to fit A, B, C of 2 isotopologues to r, θ, φ of Ar.
Halopropene fixed at monomer values
rms = 0.23 u Å2 and well-behaved correlations
Ar nearly directly above C1
EVAL used to calculate 4 closest heavy atom contacts

23. Summary
Microwave spectra are obtained and analyzed for 2,3,3,3- tetrafluoropropene and 3 isomers of chloro-3,3,3-trifluoropropene
Monomer structural parameters determined for all but (E)-1-chloro- 3,3,3-trifluoropropene
Microwave spectra are obtained and analyzed for argon complexes of all but (E)-1-chloro-3,3,3-trifluoropropene and argon atom located
Work on (E)-1-chloro-3,3,3-trifluoropropene is on-going and is being initiated for both isomers of 1,3,3,3-tetrafluoropropene
Comparison of structural trends is forthcoming
2,3,3,3-tetrafluoropropene – HCl has been observed and assigned
Spectra of other halopropene/HX mixtures (X = F, Cl) have been obtained but spectra of complexes not yet assigned.