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Theoretical and experimental studies on concerted elimination of 1, 2‐bromochloroethane monocation to C 2 H 4 + and BrCl
Author(s) -
Wu Hua,
An Mengdi,
Wen Junqing,
Bai Lihua,
Li Dongming,
Liu Jukun,
Sun Ruijuan,
He Wanlin,
Lin Lin,
Li Yumei
Publication year - 2021
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.26433
Subject(s) - ab initio quantum chemistry methods , ab initio , density functional theory , chemistry , moiety , analytical chemistry (journal) , molecule , computational chemistry , stereochemistry , organic chemistry , chromatography
Ab initio calculations for the concerted elimination of 1, 2‐bromochloroethane monocation (1,2‐C 2 H 4 BrCl + ) to C 2 H 4 + and BrCl are performed using the Minnesota density functional M06‐2X and the def2‐TZVP basis set. Ab initio calculations are also carried out for the concerted elimination of 1,2‐C 2 H 4 BrCl + to C 2 H 4 and BrCl + because the positive charge can be assigned to either moiety in the dissociative ionization process of 1,2‐C 2 H 4 BrCl + . Our results demonstrate that the concerted elimination channel of 1,2‐C 2 H 4 BrCl + to C 2 H 4 + and BrCl is preferred and that 1,2‐C 2 H 4 BrCl + surpasses two energy barriers and then separates into C 2 H 4 + + BrCl through an asynchronous concerted process. Experimentally, we confirm that this elimination channel is from the dissociative ionization process of 1,2‐C 2 H 4 BrCl + by using dc‐slice imaging technique. The time‐of‐flight mass spectra of 1,2‐bromochloroethane induced by femtosecond laser pulses show that C 2 H 4 + occurs at a laser intensity of 6.0 × 10 13 W/cm 2 , and BrCl + occurs at a higher laser intensity than C 2 H 4 + . This finding is consistent with the theoretical result that the appearance energy of C 2 H 4 + is lower than that of BrCl + . As such, the low‐velocity component of BrCl + is absent from our sliced images.