Investigation of Transition state and Kinetics of the reaction of NCO+O By Ruchira Silva

Over view Back ground Back ground Experimental Results Experimental Results Recent theoretical results Recent theoretical results Selected project and calculation Selected project and calculation Results Results Conclusion Conclusion

Why NCO + O ? NO x emission effects - air quality NO x emission effects - air quality Three sources of NO x formation Three sources of NO x formation NCO – key in two mechanism NCO – key in two mechanism

Three reaction paths NCO (X 2 Π) + O( 3 P)NO (X 2 Π) + CO (X1 ∑ ) NCO (X 2 Π) + O( 3 P)NO (X 2 Π) + CO (X1 ∑ ) NCO (X 2 Π) + O( 3 P)N ( 4 S) + CO 2 (X1 ∑ ) NCO (X 2 Π) + O( 3 P)N ( 4 S) + CO 2 (X1 ∑ ) NCO (X 2 Π) + O( 3 P)N ( 2 D) + CO 2 (X1 ∑ ) NCO (X 2 Π) + O( 3 P)N ( 2 D) + CO 2 (X1 ∑ )

Experimental studies Yide Gao and R. glen Macdonald Yide Gao and R. glen Macdonald Determination of rate constant using time resolved Determination of rate constant using time resolved IR absorption spectroscopy. Rate constant = (2.1 ± 0.76) x cm 3 molecule -1 s -1 ) at 292 ± 2 K Rate constant = (2.1 ± 0.76) x cm 3 molecule -1 s -1 ) at 292 ± 2 K K.H. Becker, R.Kurtenbach, F.Schmidt and P.waesen K.H. Becker, R.Kurtenbach, F.Schmidt and P.waesen Determination of rate constant using laser induced Determination of rate constant using laser inducedflorescence Rate constant = Rate constant = Combustion and flame 120: (2000) : J.Phys.Chem.A 2003, 107,

Theoretical studies Zheng-wang Qu, Hui Zhu, Ze-sheng Li, Xing-kang Zhang and Qi- yuan Zhang Zheng-wang Qu, Hui Zhu, Ze-sheng Li, Xing-kang Zhang and Qi- yuan Zhang Reaction mechanism between CN and O 2 Reaction mechanism between CN and O 2 Reaction followed through NCO (X 2 Π) + O( 3 P) or Reaction followed through NCO (X 2 Π) + O( 3 P) or NO (X 2 Π) + CO (X1 ∑ ) channel NO (X 2 Π) + CO (X1 ∑ ) channel Z.Qu et al Chemical Physics Letters 353 (2002)

Level of theory and Basis set Geometry optimization Geometry optimization Theory – UB3LYP Theory – UB3LYP Basis set – 6-31+G(d) Basis set – 6-31+G(d) Zero point energy Zero point energy Calculated frequency + statistical method Calculated frequency + statistical method Relative energy Relative energy Theory – UCCSD(T) Theory – UCCSD(T) Basis set – G(d) Basis set – G(d)

Z.Qu et al Chemical Physics Letters 353 (2002)

TS 3/6

Z.Qu et al Chemical Physics Letters 353 (2002) ?

Geometry Optimization Initially Initially Theory and Basis set - UHF/3-21+G* Theory and Basis set - UHF/3-21+G* Finally Finally 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 calculation

Results 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 3UHF/3-21+g* UB3LYP/631G+D Structure -3

Results Struc ture Theory/basis set SCF Energy N-O4 bond length C-N bond length bond lengthC-O bond length CNO bond angle OCN bond angle 6UHF/3-21+g* UB3LYP/631G+D Structure -6

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* UB3LYP/631G+D????????????

Energy Calculation Structure 6 TS(6/3) Enthalpy using G2 (eV) ?? Enthalpy Change kcal/mol

Results Relative energies Relative energies Results Relative energies (kcal/mol) – UHF/3-21+G* Relative energies (kcal/mol) – UHF/3-21+G* Structure 3 Structure 6 TS ?

Results Relative energies (kcal/mol) – UB3LYP/6-31+G(d) Relative energies (kcal/mol) – UB3LYP/6-31+G(d) Structure 3 Structure 6 TS ?

Future plan Find the Transition state between structure (6) and (3) Find the Transition state between structure (6) and (3) Find kinetics the intermediate reaction Find kinetics the intermediate reaction Find kinetics of full reaction Find kinetics of full reaction Find a new mechanism to the reaction Find a new mechanism to the reaction

Summery NCO (X 2 Π) + O( 3 P) NO (X 2 Π) + CO (X1 ∑ ) involves multiple steps NCO (X 2 Π) + O( 3 P) NO (X 2 Π) + CO (X1 ∑ ) involves multiple steps Reaction path from 6 to 3 go through a transition state Reaction path from 6 to 3 go through a transition state Electronic structure of the TS is not common Electronic structure of the TS is not common

Acknowledgment Professor. Arthur G. Suits Professor. Arthur G. Suits Professor. H. Bernhard Schlegel Professor. H. Bernhard Schlegel Dr. Smriti Anand Dr. Smriti Anand Dr. Hrant P. Hratchian Dr. Hrant P. Hratchian Wayne State University Wayne State University My friends. My friends.