On the Electronic Character of Localized Singlet 2,2-Dimethoxycyclopentane-1,3-diyl Diradicals: Substituent Effects on the Lifetime
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- 作者：Manabu Abe ; Waldemar Adam ; Michihiro Hara ; Masanori Hattori ; Tetsuro Majima ; Masatomo Nojima ; Kei Tachibana ; and Sachiko Tojo
- 刊名：Journal of the American Chemical Society
- 出版年：2002
- 出版时间：June 12, 2002
- 年：2002
- 卷：124
- 期：23
- 页码：6540 - 6541
- 全文大小：44K
- 年卷期：v.124,no.23(June 12, 2002)
- ISSN：1520-5126
文摘
Photodenitrogenation of the diazenes 4 affords exclusively the housanes 5 through intramolecular cyclization of the spectrally detected and characterized singlet diradicals 3. The lifetime of singlet diradical 3, determined by transient absorption measurements, depends on the Y and Z substituents at the para position of the phenyl ring and has the following order: Y, Z = OMe, OMe 
OMe, CN > CN, CN > OMe, H > Cl, Cl ~ CN, H ~ Me, Me > H, H. This unprecedented substituent effect reveals stabilization of the singlet 2,2-dimethoxycyclopentane-1,3-diyl diradicals 3 through radical, zwitterionic, 
-bonding, and hyperconjugative structures.
OMe, CN > CN, CN > OMe, H > Cl, Cl ~ CN, H ~ Me, Me > H, H. This unprecedented substituent effect reveals stabilization of the singlet 2,2-dimethoxycyclopentane-1,3-diyl diradicals 3 through radical, zwitterionic, -bonding, and hyperconjugative structures.