Activation of C2H6, C3H8, and c-C3H6 by Gas-Phase Zr+ and the Thermochemistry of Zr−Ligand Complexes
| Autor: | P. B. Armentrout, M. R. Sievers |
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| Rok vydání: | 2003 |
| Předmět: | |
| Zdroj: | Organometallics. 22:2599-2611 |
| ISSN: | 1520-6041 0276-7333 |
| Popis: | The kinetic energy dependences of the reactions of Zr + ( 4 F) with ethane, propane, and cyclopropane have been studied using guided ion beam mass spectrometry. It is found that dehydrogenation is efficient and the dominant process at low energies in all three reaction systems. Efficient C-C bond activation is also observed at low energies in the cyclopropane system. At high energies, products resulting from both C-H and C-C cleavage processes are appreciable for all three hydrocarbon systems. The observation of dihydride and hydridomethyl zirconium cation products provides insight into the reaction mechanisms operating in these processes. The results for Zr + are compared with those for the first-row transition metal congener Ti + and the differences in behavior and mechanism discussed. Modeling of the endothermic reaction cross sections yields the 0 K bond dissociation energies (in eV) of D 0 (Zr + -2H) = 5.02 ′ 0.13, D 0 (Zr + -C) = 4.62 ′ 0.16, D 0 (Zr + -CH) = 5.89 ′ 0.13, D 0 (Zr + -CH 2 ) = 4.61 ′ 0.05, D 0 (Zr + -CH 3 ) = 2.36 ′ 0.10, D 0 [Zr + -(H)(CH 3 )] = 5.43 ′ 0.15, D 0 (Zr + -C 2 H) = 4.57 ′ 0.12, D 0 (Zr + -C 2 H 2 ) = 2.83 ′ 0.15, D 0 (Zr + -C 2 H 3 ) = 3.78 ′ 0.24, D 0 (Zr + -C 2 H 4 ) = 2.84 ′ 0.18, D 0 (Zr + -C 2 H 5 ) = 2.37 ′ 0.17, D 0 (Zr + -C 3 H 2 ) = 5.45 ′ 0.20, and D 0 (Zr + -C 3 H 3 ) ≥ 4.10 ′ 0.23. The observation of exothermic processes sets lower limits for the bond energies of Zr + to propyne and propene of 2.84 and 1.22 eV, respectively. |
| Databáze: | OpenAIRE |
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