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  • Computational Chemistry and Molecular Modeling  (1)
  • Hydrosilylation  (1)
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  • 1
    ISSN: 1432-2234
    Schlagwort(e): Key words: Ab initio molecular orbital methods ; Acetylene insertion ; Platinum hydride ; Platinum silyl ; Vibronic coupling ; Hydrosilylation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract. Acetylene insertion into Pt(II)–H and Pt(II)SiH3 bonds of PtH(SiH3)(PH3) was investigated using ab initio molecular orbital and Møller-Plesset perturbation theory methods. The insertion into PtH was predicted to proceed with a smaller activation energy (E a =12.8 kcal/mol) than that into PtSiH3 (E a =20.9 kcal/mol). The reaction energy (ΔE) of the insertion into PtH is 10 kcal/mol smaller than that for the insertion into PtSiH3, which reflects differences in bond energies between CH and CSi and between PtH and PtSiH3. A comparison with ethylene insertion revealed that the acetylene insertion occurs more easily, and the latter reaction is more exothermic. A simple vibronic coupling model combined with Toyozawa's interaction mode analysis was used to examine interesting differences in E a and ΔE between insertions into PtH and PtSiH3, and between acetylene and ethylene insertions. This analysis suggests that the factors determining E a are the stiffness of the PtH and PtSiH3 bonds and the vibronic coupling strength of acetylene and ethylene.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 481-491 
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Insertion of CO2 into the transition metal-hydride bond of [RhIIIH2(PH3)3]+, CuIH(PH3)2, and RhIH(PH3)3 was theoretically investigated with ab initio MO/MP4, SD-CI, and CCD methods. The geometries of reactants, transition states (TS), and products were optimized at the Hartree-Fock level, and then MP4, SD-CI, and CCD calculations were performed on those optimized structures. The TS of the CO2 insertion into the CuI(bond)H bond is the most reactantlike, while the TS of the CO2 insertion into the RhIII(bond)H bond is the most productlike. The activation energy (Ea) and the reaction energy (ΔE) were calculated to be 6.5 and -33.5 kcal/mol for the CO2 insertion into the Cu1(bond)H bond, 21.2 and -7.0 kcal/mol for the CO2 insertion into the Rh1(bond)H bond, and 51.3 and -1.1 kcal/mol for the Rh111(bond)H bond at the SD-CI level, where negative ΔE represents exothermicity. These results are discussed in terms of the M(bond)H bond energy and the trans-influence of the hydride ligand. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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