investigation of transition state and kinetics of the reaction of nco+o by ruchira silva

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.