Transcript Investigation of Transition state and Kinetics of the

Investigation of Transition state
and Kinetics of the reaction of
NCO+O
By
Ruchira Silva
Over view
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Back ground
Experimental Results
Recent theoretical results
Selected project and calculation
Results
Conclusion
Why NCO + O ?
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NOx emission effects - air quality
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Three sources of NOx formation
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NCO – key in two mechanism
Three reaction paths
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NCO (X2Π) + O(3P)
NO (X2Π) + CO (X1∑)
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NCO (X2Π) + O(3P)
N (4S) + CO2 (X1∑)
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NCO (X2Π) + O(3P)
N (2D) + CO2 (X1∑)
Experimental studies
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Yide Gao and R. glen Macdonald
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Determination of rate constant using time resolved
IR absorption spectroscopy.
Rate constant = (2.1 ± 0.76) x 10-10 cm3molecule-1s-1) at 292 ± 2 K
K.H. Becker, R.Kurtenbach, F.Schmidt and P.waesen
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Determination of rate constant using laser induced
florescence
Rate constant =
Combustion and flame 120:570-577 (2000) : J.Phys.Chem.A 2003, 107, 4625-4635
Theoretical studies
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Zheng-wang Qu, Hui Zhu, Ze-sheng Li,
Xing-kang Zhang and Qi- yuan Zhang
Reaction mechanism between CN and O2
 Reaction followed through NCO (X2Π) + O(3P) or
 NO (X2Π) + CO (X1∑) channel
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Z.Qu et al Chemical Physics Letters 353 (2002) 304-309
Level of theory and Basis set
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Geometry optimization
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Zero point energy
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Theory – UB3LYP
Basis set – 6-31+G(d)
Calculated frequency + statistical method
Relative energy
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Theory – UCCSD(T)
Basis set – 6-311+G(d)
Z.Qu et al Chemical Physics Letters 353 (2002) 304-309
Z.Qu et al Chemical Physics Letters 353 (2002) 304-309
TS 3/6
Z.Qu et al Chemical Physics Letters 353 (2002) 304-309
?
Z.Qu et al Chemical Physics Letters 353 (2002) 304-309
Geometry Optimization
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Initially
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Theory and Basis set - UHF/3-21+G*
Finally
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Theory and Basis set – UB3LYP/6-31+G(d)
Energy calculation
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Theory and Basis set – compound (G2)
Results
Structure -3
Struc
ture
Theory/basis
set
SCF Energy
N-O
bond
length
C-N bond
length
C-O
bond
length
CNO
bond
angle
OCN
bond angle
3
UHF/3-21+g*
-240.607948411
1.4123
1.2380
1.1523
118.0638
171.8258
3
UB3LYP/631G+D
-243.191241258
1.2648
1.2643
1.1722
134.9162
159.0783
Results
Structure -6
Struc
ture
Theory/basis set
SCF Energy
N-O4
bond
length
C-N
bond
length
C-O
bond
length
CNO
bond angle
OCN
bond angle
6
UHF/3-21+g*
-240.502801357
1.2196
1.5038
1.2196
31.3160
108.8249
6
UB3LYP/631G+D
-243.13575585
1.2521
1.3947
1.2521
28.58998
119.1988
Results
Transition Structure - 6~3
Structu
re
Theory/basis
set
SCF Energy
N-O
bond
length
C-N
bond
length
C-O
bond
length
CNO
bond
angle
OCN
bond
angle
TS (6-3)
UHF/3-21+g*
-240.559018121
1.6514
1.2373
1.1571
103.3607
175.98313
TS (6-3)
UB3LYP/631G+D
??
??
??
??
??
??
Energy Calculation
Structure 6
Enthalpy using G2
(eV)
Enthalpy Change
-242.812892
TS(6/3)
Structure 6
??
-242.86762
-34.34234 kcal/mol
Results
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Relative energies (kcal/mol) –
?
TS 6-3
65.98078
Structure
6
0.00000
Structure
3
UHF/3-21+G*
Results
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Relative energies (kcal/mol) –
?
TS 6-3
34.81763
Structure
6
0.00000
Structure
3
UB3LYP/6-31+G(d)
Future plan
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Find the Transition state between structure (6)
and (3)
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Find kinetics the intermediate reaction
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Find kinetics of full reaction
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Find a new mechanism to the reaction
Summery
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NCO (X2Π) + O(3P)
involves multiple steps
NO (X2Π) + CO (X1∑)
Reaction path from 6 to 3 go through a transition
state
Electronic structure of the TS is not common
Acknowledgment
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Professor. Arthur G. Suits
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Professor. H. Bernhard Schlegel
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Dr. Smriti Anand
Dr. Hrant P. Hratchian
Wayne State University
My friends.