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Matrix Isolation and Spectroscopic Characterization of Perfluorinated ortho ‐ and meta ‐Benzyne
Author(s) -
Wenk Hans Henning,
Sander Wolfram
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010504)7:9<1837::aid-chem1837>3.0.co;2-t
Subject(s) - aryne , matrix isolation , chemistry , photodissociation , photochemistry , argon , neon , matrix (chemical analysis) , irradiation , medicinal chemistry , organic chemistry , physics , chromatography , nuclear physics
The matrix isolation and spectroscopic characterization of two C 6 F 4 isomers, the perfluorinated o ‐benzyne 4 and the m ‐benzyne 5 , is reported. UV photolysis of tetrafluorophthalic anhydride 6 in solid argon at 10 K results in the formation of CO, CO 2 , and 1,2‐didehydro‐3,4,5,6‐tetrafluorobenzene ( 4 ) in a clean reaction. On subsequent 350 nm irradiation 4 is carbonylated to give the cyclopropenone 7 . 1,3‐Didehydro‐2,4,5,6‐tetrafluorobenzene ( 5 ) was synthesized by UV irradiation of 1,3‐diiodo‐2,4,5,6‐tetrafluorobenzene ( 8 ) via 2,3,4,6‐tetrafluoro‐5‐iodophenylradical 9 . Photolysis of 8 in solid neon at 3 K produces good yields of both radical 9 and benzyne 5 , while in argon at 10 K no reaction is observed. Thus, the photochemistry in neon at extremely low temperature markedly differs from the photochemistry in argon. The formation of 5 from 8 via 9 is reversible, and annealing the neon matrix at 8 K leads back to the starting material 8 . The benzynes 4 and 5 and the radical 9 were characterized by comparison of their matrix IR spectra with density functional theory (DFT) calculations.