The product branching ratio between different products in multichannel re-actions is as important as the over-all rate of reaction,both in terms of practical applications(e.g.models of combustion or atmosphere chem-istry)in understanding the funda-mental mechanisms of such chemical reactions.A global ground state po-tential energy surface for the disso-ciation reaction of deuterated alkyl halide CD3CH2F was computed at the CCSD(T)/CBS//B3LYP/aug-cc-pVDZ level of the-ory for all species.The decomposition of CD3CH2F is controversial concerning C-F bond dissociation reaction and molecular(HF,DF,H2,D2,HD)elimination reaction.Rice-Ramsperger-Kassel-Marcus(RRKM)calculations were applied to compute the rate constants for individual reaction steps and the relative product branching ratios for the dissociation products were calculated using the steady-state approach.At the different energies stud-ied,the RRKM method predicts that the main channel for DF or HF elimination from 1,2-elimination of CD3CH2F is through a four-center transition state,whereas D2 or H2 elimination from 1,1-elimination of CD3CH2F occurs through a direct three-center elimina-tion.At 266,248,and 193 nm photodissociation,the main product CD2CH2+DF branching ratios are computed to be 96.57％,91.47％,and 48.52％,respectively;however,at 157 nm photodissociation,the product branching ratio is computed to be 16.11％.Based on these transition state structures and energies,the following photodissociation mechanisms are sug-gested:at 266,248,193 nm,CD3CH2F→absorption of a photon→TS5→the formation of the major product CD2CH2+DF;at 157 nm,CD3CH2F→absorption of a photon→D/F in-terchange of TS1→CDH2CDF→H/F interchange of TS2→CHD2CHDF→the formation of the major product CHD2+CHDF.

Shuangfei Gu;Chih-Hao Chin;Tong Zhu;John Zeng Hui Zhang

Shanghai Engineering Research Center for Molecular Therapeutics and New Drug Development,School of Chemistry and Molecular Engineering,East China Normal University,Shanghai 200062,China;NYU-ECNU Center for Computational Chemistry at NYU Shanghai,Shanghai 200122,China;Department of Chemistry,New York University,New York 10003,USA

化学物理学报（英文版）

[1]Shuangfei Gu;Chih-Hao Chin;Tong Zhu;John Zeng Hui Zhang-.Theoretical Investigations on Photodissociation Dynamics of Deuterated Alkyl Halides CD3CH2Ft)[J].化学物理学报（英文版）,2022(03):431-442

Photodissociation,Halides,CD3CH2Ft,CD3CH2F,pVDZ,Ramsperger,Kassel,elimina,photodissociation,CD2CH2+DF,TS5,terchange,CDH2CDF,CHD2CHDF,CHD2+CHDF

Theoretical,Investigations,Dynamics,Deuterated,Alkyl,branching,between,different,products,multichannel,important,all,both,terms,practical,applications,models,combustion,atmosphere,istry,understanding,funda,mental,mechanisms,such,chemical,reactions,global,ground,state,tential,energy,surface,deuterated,alkyl,halide,was,computed,CCSD,CBS,B3LYP,aug,level,ory,species,decomposition,controversial,concerning,bond,molecular,HF,elimination,Rice,Marcus,RRKM,calculations,were,applied,constants,individual,steps,relative,ratios,calculated,using,steady,approach,At,energies,stud,method,predicts,that,main,from,through,four,center,transition,whereas,occurs,direct,three,are,respectively,however,Based,these,structures,following,sug,gested,absorption,photon,formation,major,TS1,interchange,TS2

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