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Laser flash photolysis study of 10, 10‐dimethyl‐9‐anthrylidene, a carbene with nearly degenerate singlet and triplet states
Author(s) -
Admasu Atnaf S.,
Platz Matthew S.
Publication year - 1992
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610050304
Subject(s) - chemistry , flash photolysis , carbene , photochemistry , singlet state , pyridine , ultrafast laser spectroscopy , singlet oxygen , triplet state , reaction rate constant , spectroscopy , excited state , medicinal chemistry , organic chemistry , oxygen , molecule , physics , quantum mechanics , kinetics , catalysis , nuclear physics
10, 10‐Dimethyl‐9‐anthrylidene (DMA) was studied by laser flash photolysis (LFP) techniques. LFP of the requisite diazo precursor in pentane or carbon tetrachioride produced transient spectra attributed to the hydrocarbon and monochlorinated diarylmethyl radicals, respectively. In the presence of pyridine and oxygen, ylides were formed upon LFP of 10, 10‐dimethyl‐9‐diazoanthrone. However, ylides are not formed in acetonifrile or acetone. The carbene itself was not detected by transient absorption spectroscopy. The absolute rate constants for reaction of DMA with pyridine, methanol and triethylsilane are 1·96 × 10 9 , 1·8 × 10 10 , and 1·0 × 10 8 I mol −1 s −1 , respectively. It is concluded that the singlet and triplet states of DMA are essentially degenerate.