The model reactions of ethylene polymerization and hydrogenolysis of linear alkanes (propane, n-butane, and n-pentane) on the silica-supported zirconium hydrides (BSiAO) 3 Zr IV H, (BSiAO) 2 Zr IV H 2 , and (BSiAO) 2 Zr III H were studied using the DFT approach. Catalytic processes under study were shown to occur involving different surface hydrides. The ethylene polymerization was found to proceed at comparable rates on the zirconium monohydrides, (BSiAO) 3 ZrH, and dihydrides, (BSiAO) 2 ZrH 2 . Cleavage of linear alkanes on the monohydrides (BSiAO) 3 ZrH is thermodynamically unfavorable; however, the dihydrides (BSiAO) 2 ZrH 2 can act as catalysts of the process under mild conditions. Hydrides of the trivalent zirconium, (BSiAO) 2 Zr III H, can also contribute to the hydrogenolysis reaction. A feature of all the systems studied is low regioselectivity of the corresponding processes.

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The effect of counterion on the kinetics and the mechanism of styrene polymerization by monocyclopentadienyl titanium(III) complexes was examined using the DFT approach. A comparative study of three model catalytic species, namely, CpTiIIICH2Ph+ and two ion pairs of composition CpTiIIICH2Ph+A- (A- = CH3B(C6F5)3 -, B(C6F5)4 -), was carried out. Two possible pathways (I and II) of the interaction were examined and compared. It was shown that the nature of the counterion affects the thermodynamic characteristics of styrene addition to the CpTiCH2Ph+A- ion pairs. The weaker the nucleophilicity of the counterion, the higher the exothermicity of styrene addition to CpTiCH2Ph+A-. Intramolecular formation of the C−C bond in the CpTi(CH2CHPh)CH2Ph+A- adduct is characterized by the highest energy on the reaction pathway. This step is the rate-determining stage of the overall reaction.

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