investigation of transition state and kinetics of the reaction of nco+o by ruchira silva
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Investigation of Transition Investigation of Transition state and Kinetics of the state and Kinetics of the
reaction of reaction of NCO+ONCO+O
ByBy
Ruchira SilvaRuchira Silva
Over view Over view
Back groundBack ground Experimental ResultsExperimental Results Recent theoretical resultsRecent theoretical results Selected project and calculationSelected project and calculation ResultsResults ConclusionConclusion
Why NCO + O ?Why NCO + O ?
NONOxx emission effects - air quality emission effects - air quality
Three sources of NOThree sources of NOxx formation formation
NCO – key in two mechanismNCO – key in two mechanism
Three reaction pathsThree reaction paths
NCO (XNCO (X22ΠΠ)) + O( + O(33P)P) NO (XNO (X22ΠΠ)) + CO (X1 + CO (X1∑∑))
NCO (XNCO (X22ΠΠ)) + O( + O(33P)P) N (N (44S) + COS) + CO22 (X1 (X1∑∑))
NCO (XNCO (X22ΠΠ)) + O( + O(33P)P) N (N (22D) +D) + COCO22 (X1 (X1∑∑))
Experimental studiesExperimental studies
Yide Gao and R. glen MacdonaldYide Gao and R. glen Macdonald
Determination of rate constant using time resolved Determination of rate constant using time resolved IR absorption spectroscopy.IR absorption spectroscopy.
Rate constant = (2.1 Rate constant = (2.1 ± 0.76) x 10± 0.76) x 10-10-10 cmcm33moleculemolecule-1-1ss-1-1) at 292 ) at 292 ± ± 2 K2 K
K.H. Becker, R.Kurtenbach, F.Schmidt and P.waesenK.H. Becker, R.Kurtenbach, F.Schmidt and P.waesen
Determination of rate constant using laser induced Determination of rate constant using laser induced florescenceflorescence
Rate constant =Rate constant =
Combustion and flame 120:570-577 (2000) : J.Phys.Chem.A 2003, 107, 4625-4635
Theoretical studiesTheoretical studies
Zheng-wang Qu, Hui Zhu, Ze-sheng Zheng-wang Qu, Hui Zhu, Ze-sheng Li, Xing-kang Zhang and Qi- yuan Li, Xing-kang Zhang and Qi- yuan ZhangZhang
Reaction mechanism between CN and OReaction mechanism between CN and O22
Reaction followed through Reaction followed through NCO (XNCO (X22ΠΠ)) + O( + O(33P) orP) or
NO (XNO (X22ΠΠ)) + CO (X1 + CO (X1∑∑) ) channelchannel
Z.Qu et al Chemical Physics Letters 353 (2002) 304-309
Level of theory and Basis setLevel of theory and Basis set
Geometry optimizationGeometry optimization Theory – UB3LYPTheory – UB3LYP Basis set – 6-31+G(d)Basis set – 6-31+G(d)
Zero point energyZero point energy Calculated frequency + statistical methodCalculated frequency + statistical method
Relative energyRelative energy Theory – UCCSD(T)Theory – UCCSD(T) Basis set – 6-311+G(d)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
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
?
Geometry OptimizationGeometry Optimization
InitiallyInitially Theory and Basis set - UHF/3-21+G*Theory and Basis set - UHF/3-21+G*
FinallyFinally Theory and Basis set – UB3LYP/6-31+G(d)Theory and Basis set – UB3LYP/6-31+G(d)
Theory and Basis set – compound (G2)Theory and Basis set – compound (G2)
Energy calculationEnergy calculation
ResultsResults
StruStructurcturee
Theory/basis Theory/basis setset
SCF EnergySCF Energy N-O N-O bond bond lengthlength
C-N C-N bond bond lengthlength
C-O C-O bond bond lengthlength
CNO CNO bond bond angleangle
OCN OCN
bond bond angleangle
33 UHF/3-21+g*UHF/3-21+g* --240.60794841240.6079484111
1.41231.4123 1.23801.2380 1.15231.1523 118.0638118.0638 171.8258171.8258
33 UB3LYP/UB3LYP/631G+D631G+D
--243.19124125243.1912412588
1.26481.2648 1.26431.2643 1.17221.1722 134.9162134.9162 159.0783159.0783
Structure -3
ResultsResults
StruStructurcturee
Theory/basis Theory/basis setset
SCF EnergySCF Energy N-O4 N-O4 bond bond lengthlength
C-NC-N
bond bond lengthlength
C-OC-O
bond bond lengthlength
CNO CNO bond bond angleangle
OCN OCN
bond bond angleangle
66 UHF/3-21+g*UHF/3-21+g* --240.502801357240.502801357
1.21961.2196 1.50381.5038 1.21961.2196 31.316031.3160 108.8249108.8249
66 UB3LYP/631G+DUB3LYP/631G+D -243.13575585-243.13575585 1.25211.2521 1.39471.3947 1.25211.2521 28.5899828.58998 119.1988119.1988
Structure -6
ResultsResults
Transition Structure - 6~3
StructStructureure
Theory/basis Theory/basis setset
SCF EnergySCF Energy N-O N-O bond bond lengthlength
C-N C-N bond bond lengthlength
C-O C-O bond bond lengthlength
CNO CNO bond bond angleangle
OCN OCN
bond bond angleangle
TS (6-TS (6-3)3)
UHF/3-21+g*UHF/3-21+g* --240.55901812240.5590181211
1.65141.6514 1.23731.2373 1.15711.1571 103.3607103.3607 175.98313175.98313
TS (6-TS (6-3)3)
UB3LYP/UB3LYP/631G+D631G+D
???? ???? ???? ???? ???? ????
Energy CalculationEnergy Calculation
Structure 6Structure 6 TS(6/3) TS(6/3) Structure 6Structure 6
Enthalpy using G2 Enthalpy using G2 (eV)(eV)
-242.812892-242.812892 ???? -242.86762-242.86762
Enthalpy ChangeEnthalpy Change -34.34234 kcal/mol-34.34234 kcal/mol
ResultsResults
Relative energiesRelative energies
ResultsResults
Relative energies (kcal/mol) – Relative energies (kcal/mol) – UHF/3-UHF/3-21+G*21+G*
Structure 3
Structure 6
TS 6-3
0.00000
?
65.98078
ResultsResults
Relative energies (kcal/mol) – Relative energies (kcal/mol) – UB3LYP/6-UB3LYP/6-31+G(d) 31+G(d)
Structure 3
Structure 6
TS 6-3
0.00000
?
34.81763
Future planFuture plan
Find the Transition state between Find the Transition state between structure (6) and (3)structure (6) and (3)
Find kinetics the intermediate reactionFind kinetics the intermediate reaction
Find kinetics of full reactionFind kinetics of full reaction
Find a new mechanism to the reactionFind a new mechanism to the reaction
SummerySummery
NCO (XNCO (X22ΠΠ)) + O( + O(33P)P) NO (X NO (X22ΠΠ)) + CO (X1 + CO (X1∑∑) ) involves multiple stepsinvolves multiple steps
Reaction path from 6 to 3 go through a Reaction path from 6 to 3 go through a transition statetransition state
Electronic structure of the TS is not Electronic structure of the TS is not commoncommon
AcknowledgmentAcknowledgment
Professor. ArthurProfessor. Arthur G. SuitsG. Suits
Professor. H. Bernhard SchlegelProfessor. H. Bernhard Schlegel
Dr. Smriti AnandDr. Smriti Anand Dr. Hrant P. HratchianDr. Hrant P. Hratchian Wayne State UniversityWayne State University My friends.My friends.