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
URL:
http://dx.doi.org/10.1007/s002140050509
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