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Photochemistry of [2.2]Paracyclophan‐enes — a Matrix‐Isolation Study
Author(s) -
Marquardt Ralph,
Sander Wolfram,
Laue Thomas,
Hopf Henning
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619961214
Subject(s) - chemistry , matrix isolation , xylylene , photochemistry , photodissociation , singlet state , cleavage (geology) , absorption spectroscopy , ground state , argon , polymer chemistry , organic chemistry , excited state , physics , geotechnical engineering , quantum mechanics , fracture (geology) , nuclear physics , engineering
The UV photolysis of [2.2]paracyclophan‐ene ( 3 ) and benzo‐[2.2]paracyclophan‐ene ( 4 ), matrix‐isolated in argon at 10 K, results in the cleavage of the ethano bridge and formation of compounds 5 and 8 , respectively. The IR and UV/Vis spectra are compared with p ‐xylylene and the benzyl radical as models for a quinoid or diradicaloid structure. The absence of an ESR signal reveals a singlet ground state for these compounds. Remarkable is a sharp absorption in the red part of the visible spectrum which is not observed in the case of p ‐xylylene or the benzyl radical. The electronic structure can be described as quinoid with a substantial amount of diradicaloid character.