The activation of C-H bonds in C-1-C-3 alkanes by zirconium(III, IV) and titanium(III, IV) Hydrides immobilized on the surface of SiO2: A density functional theory studyстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Model reactions of the ( Si-O-)(3)(MH)-H-IV (1), ( Si-O-)(2)(MH2)-H-IV (2), and ( Si-O-)(2)(MH)-H-III (3) hydrides, where M = Ti and Zr, immobilized on the surface of silica with methane and propane were studied by the density functional theory with the PBE functional. The reactions involved the breaking of C-H alkane bonds and the formation of the ( Si-O-)(3)MR, ( Si-O-)(2)M(H)R, and ( Si-O-)(2)MR products (R = Me, n-Pr, and i-Pr), respectively. Reactions with the participation of 1 and 2 were found to occur as bimolecular processes without the formation of agostic-type prereaction complexes. With 3, the reaction was accompanied by the formation of stable prereaction and postreaction complexes. The conclusion was drawn that dihydrides 2 and trivalent metal hydrides 3 were much more reactive with respect to alkane C-H bonds than monohydrides 1. All the systems studied were characterized by low reaction regioselectivities.