Photoinduced Homolytic Bond Cleavage of the Central Si–C Bond in Porphyrin Macrocycles Is a Charge Polarization Driven Process

2016 ◽  
Vol 120 (39) ◽  
pp. 7634-7640 ◽  
Author(s):  
Buddhadev Maiti ◽  
Arun K. Manna ◽  
Christopher McCleese ◽  
Tennyson L. Doane ◽  
Sudha Chakrapani ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Charge Polarization ◽  
A Charge ◽  
Homolytic Bond Cleavage ◽  
Porphyrin Macrocycles

scholarly journals A charge polarization model for the metal-specific activity of superoxide dismutases

2018 ◽  
Vol 20 (4) ◽  
pp. 2363-2372
Author(s):  
Anna Barwinska-Sendra ◽  
Arnaud Baslé ◽  
Kevin J. Waldron ◽  
Sun Un
Keyword(s):  
Specific Activity ◽  
Angular Position ◽  
Superoxide Dismutases ◽  
Polarization Model ◽  
Charge Polarization ◽  
A Charge

EPR shows that the angular position of the histidine-171 ligand likely plays an important role in metal-selective activities of Mn/FeSODs.

New Elements on the Behaviour of a Bissulfinylmethyl Radical

2013 ◽  
Vol 66 (3) ◽  
pp. 346 ◽  
Author(s):  
Rocio Martinez Mallorquin ◽  
Guillaume Vincent ◽  
Etienne Derat ◽  
Max Malacria ◽  
Jean-Philippe Goddard ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Complex Mixtures ◽  
Homolytic Bond Cleavage

In this article, we have studied the generation of a bissulfinylmethyl radical from the corresponding TEMPO and phenylselenyl bissulfoxide precursors. No univocal formation of the bissulfinylmethyl radical has been observed. Instead, complex mixtures have been obtained in thermal or photochemical conditions, showing prominent C–S homolytic bond cleavage.

An energy-resolved study of the fragmentation reactions of alkyl ammonium ions

1994 ◽  
Vol 72 (11) ◽  
pp. 2205-2211 ◽  
Author(s):  
Nancy L. Bosma ◽  
Alex. G. Harrison
Keyword(s):  
Bond Cleavage ◽  
Centre Of Mass ◽  
Stable Secondary Structure ◽  
Ammonium Ions ◽  
Energy Profiles ◽  
Compound C ◽  
Fragmentation Reactions ◽  
Alkyl Ammonium ◽  
Homolytic Bond Cleavage ◽  
Alkane Elimination

The unimolecular metastable ion and low-energy collision-induced fragmentation reactions of alkyl ammonium ions RnH4−nN+ (n = 2 to 4, R = n-C3H7 and n-C4H9) have been studied and breakdown graphs expressing the % fragment ion abundances as a function of the centre-of-mass collision energy have been established. The dialkyl and trialkyl ammonium ions fragment primarily by olefin ([R − H]) elimination or by formation of the alkyl ion R+ (with rearrangement to the more stable secondary structure). By contrast the tetraalkyl ammonium ions show both elimination of [R − H] and elimination of an alkane, which is C5H12 for the propyl compound C7H16 for the butyl compound. The results are interpreted in terms of competition between heterolytic bond cleavage to form a [R+---NH4−nRn−1] complex and homolytic bond cleavage to form a [Rn−1H4−nN+•---•R] complex. The former complex fragments either to form R+ or undergoes internal proton transfer to form Rn−1H4−nNH+ + [R − H], while the latter complex fragments by alkane elimination resulting from attack of R• on the α-CC bond of the alkyl group. For the propyl ammonium ions plausible potential energy profiles are established which show that the former complex is favoured for n = 2, 3 while the two complexes have similar energies for n = 4.

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