1、Effect of Halogenation on the Mechanism of the Atmospheric Reactions between Methylperoxy Radicals and NO.A computational Study作者：Agnie M.Kosmas*,Zoi Salta,and Antonija Lesar出處：J.Phys.Chem.A,2009,113(15),pp 35453554 指導教授：胡維平 教授報告學生：彭家瑜報告日期：2010/03/291Abstract CH3O2+NO reaction had been discussed in
2、experimental and computational studies.The authors wanted to study the influence of halogenation about this reaction by using ab initio and DFT method.The intermediate in this reaction is CHX2OONOcp,CHX2OONOtp,and CHX2ONO2.The latter one would be decomposed to CX2O+HONO and CHXO+XNO2.Halogenation st
3、abilizes CHX2OONO and increases exothermicity in the overall reaction that is CHX2O2+NO CHX2O+NO2 suggests that halogenation enhances the reactivity.They also discussed the ambiguous issue of CHX2OONO CHX2ONO2 one-step isomerization and found triplet transition state in this reaction.2OutlinenIntrod
4、uctionnComputational Methods nResults and Discussion -RO2+NO RO+NO2 -ROONOtp RONO2 IsomerizationnConclusions3IntroductionnIn Troposphere RO2+NO ROONO RO+NO2 RO2+NO RONO2 nExperiment in 298K(cm3mol-1s-1)CF3O2+NO k=1.6x10-11 CHCl2O2+NOk=1.9x10-11 CHBr2O2+NOk=1.1x10-11 CH3O2+NO k=7.7x10-12Sander,S.P.;F
5、riedl,R.R.;Golden,D.M.;Kurylo,M.J.;Moortgat,G.K.;Wine,P.H.;Ravishankara,A.R.;Kolb,C.E.;Molina,M.J.;Finlayson-Pitts,B.J.;Huie,R.E.;Orkin,V.L.Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies:Evaluation Number 15.JPL Publication 06-2;National Aeronautics and Space Administration,
6、Jet Propulsion Laboratory,California Insitute of Technology:Pasadena,CA,2006.Sehested,J.;Nielsen,O.J.;Wallington,T.J.Chem.Phys.Lett.1993,213,457Reduction of the RO-O bond strength4IntroductionnComputational Studies CHCl2O2 is more reactive related to CH3O2+NO RO2+NO ROONO RO2+NO RONO2 R=alkyl group
7、ROONO RONO2 isomerization King,M.D.;Thomson,K.C.Atmos.Environ.2003,37,4517Lohr,L.L.;Barker,J.R.;Stroll,R.M.J.Phys.Chem.A 2003,107,7429Zhao,Y.;Houk,K.N.;Olson,L.P.J.Phys.Chem.A 2004,108,5864Barker,J.R.;Lohr,L.L.;Stroll,R.M.;Reading,S.J.Phys.Chem.A 2003,107,7434Zhang,J.;Dransfield,T.;Donahue,N.M.J.Phy
8、s.Chem.A 2004,108,9082Zhang,J.;Dransfield,T.;Donahue,N.M.J.Phys.Chem.A 2004,108,9082Zhao,Y.;Houk,K.N.;Olson,L.P.J.Phys.Chem.A 2004,108,58645Computational methodnMethod Geometry and vibrational frequencies：(U)MP2、(U)B3LYP Single-point energies：CCSD(T)Mutilevel：G2(MP2)、G3/B3LYPnBasis set 6-311+G(d,p)n
9、Program Gaussian 036Results and DiscussionnThe Mechanism of CHX2O2+NO CHX2O2+NO CHX2OONO CHX2O+NO2 CHX2ONO2 CHX2O+NO2 CHX2ONO2 CX2O+HONO CHX2ONO2 CHXO+XNO2 nThe Halogenation X=H、F、Cl7nEnergy profileCHX2O2+NOCHX2OONOcpCHX2OONOtpTS cp-tpCHX2O+NO2G3/B3LYP8-MP2-B3LYP(halogenated methyl peroxynitrite)9Re
10、sults and Discussiona Relative energy(kcal/mol)respect to CHX2O2+NO b The energy including zero-point energy10NoImagenEnergy profileCHCl2O2+NOCHCl2OONOcpCHCl2OONOtpTS cp-tpCHCl2O+NO2CHCl2ONO2CClHO+ClNO2CCl2O+HONOTS ccl2oTS cclhoG3/B3LYP11(halogenated methyl nitrate)-MP2-B3LYP12nEnergy profileCHCl2O+
11、NO2CHCl2ONO2TS ccl2oTS cclhoCClHO+ClNO2CCl2O+HONOCHF2O+NO2CHF2ONO2TS cf2oTS cfhoCFHO+FNO2CF2O+HONOG3/B3LYP13Results and Discussiona Relative energy(kcal/mol)respect to CHX2O2+NO b The energy include zero-point energy14nExperimental Results(IR spectra)Chiappero,M.S.;Burgos Paci,M.A.;Arg ello,G.A.;Wal
12、lington,T.J.Inorg.Chem.2004,43,2714CHF2O2NO2+h CHF2ONO2CHF2ONO2 CFHO+FNO2CHF2ONO2(80 10%)CFHO(1020%)15Results and DiscussionBond distances()16Results and DiscussionnROONOtp RONO2Experimental resultsRO2+NO RONO2 RO2+NO RO+NO2 RONO2 (low pressure)Computational resultsRO2+NO ROONO RO+NO2 RONO2 (low pre
13、ssure)RO2+NO ROONOtp RONO2 (moderate&high pressure)Arey,J.;Aschmann,S.M.;Kwok,E.S.C.;Atkinson,R.J.Phys.Chem.A 2001,105,1020Lesar,A.;Hodo ek,M.;Drougas,E.;Kosmas,A.M.J.Phys.Chem.A 2006,110,789817B3LYP/6-311+(d,p)nPotential Energy Curve200618Results and Discussiona Relative energy(kcal/mol)respect to
14、CHX2O2+NO b The energy including zero-point energy19nExperimental Result At near room temperature and 1atm,CF3O2+NO produce at least 3 times more CX3ONO2 than CH3O2+NO.CF3O2 k(nitrate)/k(total)=(1.670.27)x10-2 CH3O2 k(nitrate)/k(total)0.5x10-2Nishida,S.;Takahashi,K.;Matsumi,Y.;Chiappero,M.;Arg ello,
15、G.;Wallington,T.J.;Hurley,M.D.;Ball,J.C.Chem.Phys.Lett.2004,388,242Results and Discussion20ConclusionsnThe increased reactivity is attributed to the more stable CHX2OONO intermediates and the larger exothermicity of the overall reaction CHX2O2+NO CHX2O+NO2 compared to CH3O2+NO CH3O+NO2.nCHX2ONO2 formation is suggested that the singlet CHX2OONO and singlet CHX2ONO2 isomerization,through the triplet transition state.nThe computational results are in agreement with some experimental results.2122
