internal rotation in cf 3 i nh 3 and cf 3 i n(ch 3 ) 3 probed by cp-ftmw spectroscopy nicholas r....
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Internal Rotation in CF3INH3 and CF3I N(CH3)3
Probed by CP-FTMW SpectroscopyNicholas R. Walker, Susanna L. Stephens, Anthony C. Legon
66th OSU International Symposium on Molecular Spectroscopy
1
19th June, 2011.
Rcm
N I
Engineering and Physical Sciences Research Council
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Introduction
1) Halogen bond describes attractive interaction between electron donor (e.g. NH3) and a halogen atom.
2) Significance of IN interaction in solid-state technology exploiting halogen bonds. Iodoperfluoroalkanes are standard “building blocks” because electron-withdrawing CF2 units allow stronger interactions of the iodine atom.
3) CF3INH3 and CF3IN(CH3)3 excellent targets for CP-FTMW spectroscopy. Extensive hyperfine structure, many bands between 8-18 GHz.
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Power divider
SPST switch
MixerMixer
Low noise amplifier
Pin diode limiter
Adjustable attenuator
5W Power amplifier
AWG (0.5- 12 GHz)
Oscilloscope (0- 12 GHz)
10 MHz reference frequency
PDRO (19.00 GHz)
7.0 - 18.5 GHz 7.0 - 18.5 GHz
12.2 GHz Low- pass band filter
CP-FTMW Spectrometer
300 W TWT Amplifier
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OCS
590 790 990 1190 Units are microsecondstime
FID intensity
Multi-chirp excitation
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8000 10000 12000 14000 16000 18000Energy/MHz
13840 13860 13880 13900Energy/MHz
CF3I
CF3INH3 ??
8000 10000 12000 14000 16000 18000Energy/MHz
13840 13860 13880 13900Energy/MHz
CF3INH3
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Rcm
N I
[1] G. T. Fraser, F. J. Lovas, R. D. Suenram, D. D. Nelson, Jr. and W. Klemperer, J. Chem. Phys. 1986, 84, 5983-5988. [2] G. Valerio, G. Raos, S. V. Meille, P. Metrangolo and G. Resnati, J. Phys. Chem. A, 2000, 104, 1617-1620.
C3v Symmetric top ?Internal rotation?
22220R )1())1()(( JJDJJKmDmDKDBH JJKmmJJΚ
The Hamiltonian
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13850 13860 13870
Energy/MHz
Exp.
Sim. [80 kHz FWHM]
Energy/MHz13850 13855 13860 13865 13870 13875
A species sim.
E species sim.
Total (A and E) sim.
Simulation and fitting using PGOPHER (2010, version 7.0.103), a Program for Simulating Rotational Structure, C. M. Western, University of Bristol, http://pgopher.chm.bris.ac.uk.
CF3I14NH3
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10370 10380 10390
Energy/MHz
Sim.
Exp.
CF3I14NH3
10150 10160 10170
Energy/MHz
Exp.
Sim.
CF3I15NH3
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A species CF3I15NH3 CF3I14NH3
/ MHz 848.26550(19)a 866.68032(21)DJ / kHz 0.1041(15) 0.0988(17)
DJK / kHz 1.230(37) 1.531(16) / MHz 2229.944(77) 2230.241(90) / MHz 3.337(51)N 76 189r.m.s/ kHz 6.7 11.6E species / MHz 848.26550b 866.68032c
DJ / kHz 0.1060(12) 0.0931(12)
DJK / kHz 1.285(31) 1.489(33)
DJm / kHz 36.81(34) 39.76(38)
DJKm / kHz 11.204(36) 11.365(39) / MHz 2230.186(66) 2230.124(75) / MHz 3.151(42)N 154 282r.m.s/kHz 7.4 11.1
(I)aa(N)aa
(N)aa
0B
(I)aa
0B
a Numbers in parentheses are one standard deviation in units of the last significant figure. b Fixed to the value of B0 determined for CF3I
15NH3. c Fixed to the value of B0 determined for CF3I
14NH3.
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A species CF3I15N(CH3)3 CF3I14N(CH3)3 CF3I14N(CH3)3CP-FTMW CP-FTMW CP-FTMW
( < 10 GHz) / MHz 437.88712(19)a 440.74496(11) 440.74496b
DJ 102 / kHz 2.793(37) 2.950(30) 2.950 b
/ MHz 2240.40(20) 2241.61(17) 2241.61 b
/ MHz 4.761c 4.761(88)N 318 452 74r.m.s/ kHz 32.2 18.9 11.8
E species / MHz 437.88712d 440.74496e
DJ 102 / kHz 2.96(10) 2.891(58)
DJm / kHz 29.06(49) 29.71(31)
DJKm / kHz 1.691(45) 1.698(38) / MHz 2240.70(50) 2241.62(47) / MHz 4.761c
N 147 201r.m.s/kHz 26.3 22.3
a Numbers in parentheses are one standard deviation in units of the last significant figure. b Fixed to the values determined by fitting all transitions in the broadband spectrum. c Fixed to = 4.761 MHz, determined by fitting to selected transitions below 10 GHz.
0B
(I)aa(N)aa
0B
(I)aa(N)aa
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Rcm
N I
2ICF
2ICF
2NH
2NH
2 sin2
cos12
sin2
cos12
3333aabbccbb
cmSbb
IIIIRMI
3.054 Å > rNI > 3.034 Å for CF3INH3 where 30>>0 and 8>>0
2.790 Å > rNI > 2.769 Å for CF3IN(CH3)3 where 30>>0 and 8>>0
Structure
(N)aa implies = 20.5(12) for CF3INH3 and = 16.2(20) for CF3IN(CH3)
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V. Amico, S. V. Meille, E. Corradi, M. T. Messina and G. Resnati, J. Am. Chem. Soc. 1998, 120, 8261-8262.
E. Corradi, S. V. Meille, M. T. Messina, P. Metrangolo and G. Resnati, Tetrahedron Lett. 1999, 40, 7519-7523.
rNI=2.84(3) Å.
rNI close to 2.80 Å.
2.790 Å > rNI > 2.769 Å for CF3IN(CH3)3 where 30>>0 and 8>>0
3.054 Å > rNI > 3.034 Å for CF3INH3 where 30>>0 and 8>>0
Correspondence with solid state
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Acknowledgements
University of BristolSusanna StephensTony C. LegonRuth OvalColin M. Western
University of VirginiaBrooks H. PateStephen T. Shipman
Financial Support
Engineering and Physical Sciences Research Council
University of SheffieldMichael Hippler
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8000 10000 12000 14000 16000 18000Energy/MHz
CF3I14N(CH3)3
CF3I
8790 8800 8810 8820 8830 8840Energy/MHz
Exp.
A and E species sim.
CF3I14N(CH3)3