Cations fragments centred

Glycine anion (230) is decarboxylated when exposed to hydroxyl radicals. The major initial product is an amino radical cation (231), which suffers rapid 100 ns) fragmentation into CO2 and a carbon-centred radical (232). Oxidative decarboxylation... 

The mechanism proposed for the formation of the sepulchrates accounts for the fact that, despite seven chiral centres and six nitrogen-metal bonds, the synthesis of [Co(sep)] + cation yields only one isomer. After the formation of the first heminal diamine and second imine centre, the chiral nitrogen centre must be oriented so that the methylene unit of the amine fragment and the proton are apical and equatorial, respectively, before intramolecular cycli-zation. In this case, six-membered ring closure takes place. The same apical orientation of the six-membered chelate cycle must be retained to complete the formation of a capping group. After the completed encapsulation, the methylene unit and the proton cannot... 

In the quantiun-chemical calculation the active surface of support was modelled by the cluster consisting of an acidic (H ) and basic sites - jSi-O and =Si=0 fragments of SiOj (similar to [6]). The data obtained confirmed the step-wise cyclodehydration mechanism of 1,4-BD conversion into THF suggested in [7] for the bifunctional modified ZSM-5 catalysts. This mechanism includes the 1,4-BD interaction with support H centre leading to the dehydration and, subsequently, to the formation of linear and cyclic (I) cations as intermediates (Scheme 1) ... 

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