Photo-Induced Electron Transfer Reaction of Polysilanes. Intramolecular Trapping of a Transient Silyl Radical Cation with a Nucleophile

1991 ◽  
Vol 20 (2) ◽  
pp. 327-330 ◽  
Author(s):  
Yasuhiro Nakadaira ◽  
Akira Sekiguchi ◽  
Yasuhito Funada ◽  
Hideki Sakurai
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Silyl Radical ◽  
Photo Induced Electron Transfer

Elektronenreiche Olefine, 3 / Electron Rich Olefins, 3

1989 ◽  
Vol 44 (5) ◽  
pp. 511-518 ◽  
Author(s):  
Christian Bessenbacher ◽  
Wolfgang Kaim
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Photoelectron Spectroscopy ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Membered Ring ◽  
Electron Pairs ◽  
Planar Conformation

Exhaustive reductive silylation of 2-trimethylsilyl-1,2,3-triazole (1) using Me,SiCl/K yields the new E-1,1,4,4-tetrakis(trimethylsilyl)-l,4-diazabutene(2) (4) as final product together with N(SiMe3)3. Initial reductive 1,4-addition to 1 leads to formation of 1.2.3-tris(trimethylsilyl)-1,2,3-triazoline(4) (2) as an intermediate which is rapidly reduced and silylated further to give the butene 4. Partial π overlap within the five-membered ring 2 containing 8 π electrons and three neighbouring unshared electron pairs is evident from NMR shifts and electron transfer reaction with TCNE. Photoelectron spectroscopy of 4 and the lability of its radical cation 4+. as studied by ESR show that this system cannot adopt a planar conformation in contrast to the tetrazene(2) analogue.

14N/15N and12C/13C Equilibrium Isotope Effects on the Electron-Transfer Reaction betweenN-Methylphenothiazine and Its Radical Cation

1999 ◽  
Vol 103 (35) ◽  
pp. 6998-7007 ◽  
Author(s):  
Jianming Lü ◽  
Yadong Chen ◽  
Xiaoling Wen ◽  
Long-Min Wu ◽  
Xueqing Jia ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Transfer Reaction ◽  
Isotope Effects ◽  
Electron Transfer Reaction

A pulse radiolysis study of the reactions of hydrogen atoms with dimethyl-, tetramethyl- and hexamethyl-substituted viologens

1984 ◽  
Vol 37 (8) ◽  
pp. 1579 ◽  
Author(s):  
NA McAskill
Keyword(s):  
Electron Transfer ◽  
Radical Cation ◽  
Pulse Radiolysis ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Methyl Groups ◽  
Transient Species ◽  
Hydrogen Atoms ◽  
Abstraction Reaction

The reactions of ·H, ·OH and e-aq with four viologens in aqueous solution were studied by spectrophotometry. With 1,1'-dimethyl-4,4'-bipyridinium dichloride, the main transient species caused by H reaction is the viologen radical cation formed by an electron-transfer reaction. Smaller amounts of a hydrogen-deficient radical are also formed by an abstraction reaction at one of the methyl groups together with a radical formed by addition of ·H to one of the rings. There is no evidence that a protonated radical cation species was formed. A similar pattern of reactivity is seen with 1,1',2,2'-tetra-methyl-4,4'-bipyridinium diperchlorate. However, the electron-transfer reaction is either absent in the case of 1,1',3,3'-tetramethyl-4,4'-bipyridinium diperchlorate or less important in 1,1',2,2',6,6'- hexamethyl-4,4'-bipyridinium dichloride, and the main initial transient is assigned to a hydrogen-deficient radical formed by an abstraction reaction at one of the ring methyl groups. The possible role of the hydrogen-deficient radical in reducing the loss of viologen observed in the photochemical splitting of water is discussed.

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