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Volumn , Issue , 2006, Pages 119-161

Efficient and Selective Hydrosilylation of Alkenes and Alkynes Catalyzed by Novel N-Heterocyclic Carbene Pt0 Complexes

Author keywords

Catalyzed by novel N heterocyclic carbene Pt0 complexes; Efficient and selective hydrosilylation of alkenes; Hydrosilylation of alkynes; Kinetic and mechanistic studies; N heterocyclic carbenes; Structure and reactivity of (NHC)Pt(dvtms) complexes; Synthesis

Indexed keywords


EID: 84872836681     PISSN: None     EISSN: None     Source Type: Book    
DOI: 10.1002/9783527609451.ch6     Document Type: Chapter
Times cited : (15)

References (105)
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    • We observed that the formation of colloids was concommitant with the hydrogenation of the isomerised alkene
    • We observed that the formation of colloids was concommitant with the hydrogenation of the isomerised alkene.
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    • Warhurst, N. J. W. Ph.D. Thesis, University of Sussex, 1990.
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    • Warhurst, N.J.W.1
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    • Abel, E. W., Stone, F. G. A., Wilkinson, G., Pergamon, Oxford
    • Hartley, F. R. in Comprehensive Organometallic Chemistry ed. Abel, E. W., Stone, F. G. A., Wilkinson, G., Pergamon, Oxford, 1982, vol. 6, p. 474.
    • (1982) Comprehensive Organometallic Chemistry , vol.6 , pp. 474
    • Hartley, F.R.1
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    • Vinyl silanes are excellent ligands for late, low-valent transition metals. It has been suggested that the coordinating ability of vinyl silanes is mostly due to the Si-C=C (dp-pp) interaction, which allows delocalization of the alkene's electron density onto the silicon atom via its d-orbitals. This results in enhanced back-bonding between the metal centre and the olefin delocalized p* orbital. Therefore, greater thermal stability of the vinylsilane-containing complexes relative to their carbon analogues is observed
    • Vinyl silanes are excellent ligands for late, low-valent transition metals. It has been suggested that the coordinating ability of vinyl silanes is mostly due to the Si-C=C (dp-pp) interaction, which allows delocalization of the alkene's electron density onto the silicon atom via its d-orbitals. This results in enhanced back-bonding between the metal centre and the olefin delocalized p* orbital. Therefore, greater thermal stability of the vinylsilane-containing complexes relative to their carbon analogues is observed.
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  • 67
    • 84889310425 scopus 로고    scopus 로고
    • Under "normal" conditions, the Pt complexes 14a to 14c are added to a mixture of silane 9 and olefin 10. The "inverse" protocol implies the addition of the silane 9 to a mixture of alkene 10 and Pt catalysts 14a to 14c. No colloidal Pt is formed upon increasing the amount of Pt-carbene catalysts from 30 up to 300 ppm. The rate increases concomitantly with the amount of catalyst, and the reaction can become highly exothermic
    • Under "normal" conditions, the Pt complexes 14a to 14c are added to a mixture of silane 9 and olefin 10. The "inverse" protocol implies the addition of the silane 9 to a mixture of alkene 10 and Pt catalysts 14a to 14c. No colloidal Pt is formed upon increasing the amount of Pt-carbene catalysts from 30 up to 300 ppm. The rate increases concomitantly with the amount of catalyst, and the reaction can become highly exothermic.
  • 68
    • 84889454931 scopus 로고    scopus 로고
    • The high selectivity observed with this "inverse" procedure stems from the kinetics of the hydrosilylation reaction using (NHC)Pt(dvtms) complexes, which differ significantly from the Karstedt-catalyzed system. To obtain a fair comparison between the two catalysts, both reactions have been performed under identical, nonoptimized conditions
    • The high selectivity observed with this "inverse" procedure stems from the kinetics of the hydrosilylation reaction using (NHC)Pt(dvtms) complexes, which differ significantly from the Karstedt-catalyzed system. To obtain a fair comparison between the two catalysts, both reactions have been performed under identical, nonoptimized conditions.
  • 69
    • 84889293991 scopus 로고    scopus 로고
    • Hydrosilylation of alcohol-containing substrates using the Karstedt catalyst results in significant formation of the corresponding silyl ethers (up to 40%)
    • Hydrosilylation of alcohol-containing substrates using the Karstedt catalyst results in significant formation of the corresponding silyl ethers (up to 40%).
  • 70
    • 84889408774 scopus 로고    scopus 로고
    • The high reactivity of the Karstedt catalyst precludes its use in the case of epoxide-bearing substrates. For example, more than 50% of vinyl cyclohexyl epoxide (Table 6.4, entry 5) is decomposed in the presence of this complex
    • The high reactivity of the Karstedt catalyst precludes its use in the case of epoxide-bearing substrates. For example, more than 50% of vinyl cyclohexyl epoxide (Table 6.4, entry 5) is decomposed in the presence of this complex.
  • 71
    • 84889284952 scopus 로고    scopus 로고
    • Whilst most hydrosilylations are complete within 2-4 h, the reaction of allylacetone with 14b, under identical conditions, requires up to 24 h to reach 80% conversion (Table 6.4, entry 6). In the case of the platinum-carbene complex 14b, the catalyst is still active and prolonged reaction time leads to full conversion
    • Whilst most hydrosilylations are complete within 2-4 h, the reaction of allylacetone with 14b, under identical conditions, requires up to 24 h to reach 80% conversion (Table 6.4, entry 6). In the case of the platinum-carbene complex 14b, the catalyst is still active and prolonged reaction time leads to full conversion.
  • 72
    • 84889369293 scopus 로고    scopus 로고
    • All the hydrosilylations performed using the carbene complex 10b afford crude products that are at least 95% pure and that typically contain less than 2% of isomerized alkene. With Karstedt catalyst 8, yellow solutions, including colloidal platinum species, are generated. The purity of the crude reaction mixtures varies between 72 and 92% and the amount of isomerized alkene oscillates between 5 and 11%. In the case of epoxide-containing substrates, extensive decomposition is observed
    • All the hydrosilylations performed using the carbene complex 10b afford crude products that are at least 95% pure and that typically contain less than 2% of isomerized alkene. With Karstedt catalyst 8, yellow solutions, including colloidal platinum species, are generated. The purity of the crude reaction mixtures varies between 72 and 92% and the amount of isomerized alkene oscillates between 5 and 11%. In the case of epoxide-containing substrates, extensive decomposition is observed.
  • 73
    • 84889278586 scopus 로고    scopus 로고
    • It was necessary to heat for several hours at 60 °C complex 8 in the presence of the imidazolinium salt and KOtBu to obtain good yields of the desired complex
    • It was necessary to heat for several hours at 60 °C complex 8 in the presence of the imidazolinium salt and KOtBu to obtain good yields of the desired complex.
  • 105
    • 84889390857 scopus 로고    scopus 로고
    • The electronic effect of alkoxy groups on silicon does not correlate in a simple way with their electronegativity and their influence is difficult to rationalize
    • The electronic effect of alkoxy groups on silicon does not correlate in a simple way with their electronegativity and their influence is difficult to rationalize.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.