†) Currently at Department of Chemistry, University of Manitoba A Microwave Study of the HNO 3...
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Transcript of †) Currently at Department of Chemistry, University of Manitoba A Microwave Study of the HNO 3...
††) Currently at ) Currently at Department of Chemistry, University of ManitobaDepartment of Chemistry, University of Manitoba
A Microwave Study of theA Microwave Study of the
HNOHNO33-N(CH-N(CH33))33 Complex Complex
Galen SedoGalen Sedo,,†† Kenneth R. Leopold Kenneth R. Leopold
Department of Chemistry, University of MinnesotaDepartment of Chemistry, University of Minnesota
HH22O-HX & (HO-HX & (H22O)O)22-HX-HX
• Z. Kisiel, A. C. Legon, D. J. Millen, J. Mol. Struct. 1984, 112, 1-8.
• A. C. Legon, L. C. Willoughby, Chem. Phys. Lett. 1983, 95, 449-452.• A. C. Legon, A. P. Suckley, Chem. Phys. Lett. 1998, 150, 153-158.• Z. Kisiel et al., J. Chem. Phys. 2003, 119, 5907-5917.
HCOOH-HHCOOH-H22O, HCOOH-(HO, HCOOH-(H22O)O)22 & (HCOOH) & (HCOOH)22-H-H22OO
• D. Priem, T.-K. Ha, A. Bauder, J. Chem. Phys. 2000, 113, 169-175.
CFCF33COOH-HCOOH-H22O, CFO, CF33COOH-(HCOOH-(H22O)O)22 & CF & CF33COOH-(HCOOH-(H22O)O)33
• B. Ouyang, T. G. Starkey, B. J. Howard, J. Phys. Chem. A 2007, 111, 6165-6175.
Acid Ionization in Microsolvated Acid Ionization in Microsolvated SystemsSystems
Kenneth R. Leopold GroupKenneth R. Leopold Group
• H3CCOOH-H2O
• H2SO4 [2008], H2SO4-H2O [2002, 2006]
• HNO3 [2005], HNO3-H2O [1998], HNO3-(H2O)2 [2008], HNO3-(H2O)3 [submitted]
Acid Ionization with Increasing Acid Ionization with Increasing Binding Partner BasicityBinding Partner Basicity
(CH(CH33))nnHH3-n3-nN-HXN-HX
• A. C. Legon, Chem. Soc. Rev. 1993, 153-163.
HH33N-HXN-HX
• Determined the whole series of complexes to be best described by a neutral pair
(CH(CH33))33N-HXN-HX
• Determined the ionization to progress along the series of complexes
• Ion pair formation is dominant in X = Br, I
HH33N-HNON-HNO33
• M. E. Ott, K. R. Leopold, J. Phys. Chem. A 1999, 103, 1322-1328.
• rAH is the “covalent” AH bond within the acid
• rH···B is the hydrogen bond length of the complex
• rHB+ is the covalent HB bond within the free ion
pt> 0 indicates proton transfer.
pt = 0 indicates equal sharing of proton.
pt< 0 indicates neutral pair.
Proton Transfer in Hydrogen Bound SystemsProton Transfer in Hydrogen Bound Systems
a) I. J. Kurnig, S. Scheiner, Int. J. Quantum Chem., QBS 1987, 14, 47.
free
HB
complexBH
freeAH
complexAHpt rrrr
A H H B
rAHfree rH...B
rAHcomplex
The parameter rho (pt) has been deviseda to quantify proton transfer in
hydrogen bonded systems.
HNO3-H2OHNO3-(H2O)2
HNO3-(H2O)3
Proton Transfer in Nitric Acid SystemsProton Transfer in Nitric Acid Systems
H3N-HNO3pt = -0.666 Å
pt = -0.786 Åpt = -0.644 Å
pt = -0.539 Å
(H2O)2 pt = -1.04 Å
○ Theoretical Structure ● Experimental Structure
1414N Quadrupole Coupling ConstantsN Quadrupole Coupling ConstantsNitrate IonNitrate Ion
eQq = 0.656 MHza
a) Adachi, A.; Kiyoyama, H.; Nakahara, M.; Masuda, Y.; Yamatera, H.; Shimizu, A.; Taniguchi, Y. J. Chem. Phys. 1989, 90, 392.
a
ab
b
c
c
1414N Quadrupole Coupling ConstantsN Quadrupole Coupling ConstantsNitric Acid HydratesNitric Acid Hydrates
eQq (NO3–) ↔ cc
aa + bb + cc = 0
cc = ־½[aa + (bb - cc)]
a
b
b
c
c
a
HNO3-H2O
b
b
c
c
a
a
HNO3-(H2O)2
b
b
c
c
a
a
HNO3-(H2O)3 H3N-HNO3
Nitric Acid Ionization due to Nitric Acid Ionization due to Increasing Binding Partner BasicityIncreasing Binding Partner Basicity
HH33N-HNON-HNO33
• Both methods show an increase in HNO3 ionization compared to the Nitric Acid Monohydrate.
• Ionization is comparable to that of the Nitric Acid Dihydrate.
• Complex is best described as a neutral pair.
(CH(CH33))33N-HNON-HNO33
Fourier Transform Microwave SpectrometerFourier Transform Microwave Spectrometer
• Range: 3 to 18 GHz
• Typical resolution: ~5 kHz
• Pulse Nozzle (Multiple Configurations)
• Fabry-Perot Cavity (Resonance Chamber)
• 20 inch Diffusion Pump (~5 x 10-6 torr)
Fourier Transform Microwave SpectrometerFourier Transform Microwave Spectrometer
• Pulse Nozzle (Multiple Configurations)
Series 9Pulsed Solenoid Valve
Needle Adaptor
6059.25 6059.75 6060.25
6083.5 6084.0 6084.5 6085.0 6085.5 6086.0
Frequency [MHz]
(CH(CH33))331414N-HN-H1414NONO33
332222 ← 2 ← 22121
Frequency [MHz]
I1
I2
I1 [HNO3]
I1 [HNO3]
I2 [(CH3)3N]
(CH(CH33))331515N-HN-H1414NONO33
332222 ← 2 ← 22121
6083.5 6084.0 6084.5 6085.0 6085.5 6086.0
I2 [(CH3)3N]
I1 [HNO3]
(CH(CH33))331414N-HN-H1414NONO33
332222 ← 2 ← 22121
Frequency [MHz]
(CH(CH33))331414N-HN-H1414NONO33 (RMS) = 2.5 kHz(RMS) = 2.5 kHz
111 Transitions (including hyperfine)
(CH(CH33))331515N-HN-H1414NONO33 (RMS) = 4.6 kHz(RMS) = 4.6 kHz
37 Transitions (including hyperfine)
A = 3654.80(17) MHzB = 1048.85105(11) MHzC = 979.41064(10) MHzJ = 0.0001996(47) MHzJK = 0.001273(24) MHzaa = –3.28901(63) MHzbb-cc = –0.5810(16) MHzaa = –0.3504(11) MHzbb-cc = –0.4036(28) MHz
Nitric Acid Ionization due to Nitric Acid Ionization due to Increasing Binding Partner BasicityIncreasing Binding Partner Basicity
A = 3654.80(17) MHzB = 1048.85105(11) MHzC = 979.41064(10) MHz
A = 3704.100 MHzB = 1044.807 MHzC = 975.031 MHz
15N Isotope Shift
202 ← 101 = 16.661 MHz
15N Isotope Shift
202 ← 101 = 17.33 MHz
Experimental
Theory MP2/6-311++G(2df,2pd)
(CH(CH33))331414N-HN-H1414NONO33 (RMS) = 2.5 kHz(RMS) = 2.5 kHz
111 Transitions (including hyperfine)
(CH(CH33))331515N-HN-H1414NONO33 (RMS) = 4.6 kHz(RMS) = 4.6 kHz
37 Transitions (including hyperfine)
Nitric Acid Ionization due to Nitric Acid Ionization due to Increasing Binding Partner BasicityIncreasing Binding Partner Basicity
(CH(CH33))33N-HNON-HNO33
HNO3-(H2O)2
pt = -0.644 Å
HNO3-(H2O)3
pt = -0.539 Å
HNO3-H2O
pt = -0.786 Å
pt = -0.367 Å
H3N-HNO3
pt = -0.666 Å
○ Theoretical Structure ● Experimental Structure
(H2O)2pt = -1.04 Å
Nitric Acid Ionization due to Nitric Acid Ionization due to Increasing Binding Partner BasicityIncreasing Binding Partner Basicity
cc = - ½ [aa + (bb - cc)]
cc = 0.3773(57) MHz
H14NO3 Quadrupole Coupling Constants
aa = -0.3504(11) MHz
bb – cc = -0.4036(28) MHz
(CH(CH33))33N-HNON-HNO33
Nitric Acid Ionization due to Nitric Acid Ionization due to Increasing Binding Partner BasicityIncreasing Binding Partner Basicity
ConclusionsConclusions
1. The microwave spectrum of the nitric acid trimethylamine complex
has been observed. The available experimental data are in agreement
with the theoretical MP2/6-311++G(2df,2pd) geometry.
2. Increasing the basicity of the nitric acid binding partner over the
series H2O → NH3 → N(CH3)3 promotes ionization of the acid, but
all of the 1:1 complexes are best described as neutral pairs.
Research Funding
• National Science Foundation (NSF)
• Petroleum Research Fund (PRF)
• Minnesota Supercomputing Institute (MSI)
University of Minnesota • Dr. Kenneth R. Leopold
Acknowledgements
University of Manitoba• Dr. Jennifer van Wijngaarden