Photochemical and Thermal Isomerization between Isomers of Tetrasilyldisilenes.
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Accession number;99A0308711
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| Title;Photochemical and Thermal Isomerization between Isomers of Tetrasilyldisilenes. |
| Author;
OHYA S
(Tohoku Univ., Sendai)
IWAMOTO T
(Tohoku Univ., Sendai)
ICHINOHE M
(Tohoku Univ., Sendai)
KABUTO C
(Tohoku Univ., Sendai)
KIRA M
(Tohoku Univ., Sendai)
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Journal Title;Abstr Symp Organomet Chem Jpn
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Journal Code:L0853A
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ISSN:
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VOL.45th;NO.;PAGE.36-37(1998)
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| Figure&Table&Reference; |
| Pub. Country;Japan |
| Language;English |
| Abstract;Temperature-dependent 29Si NMR spectra of SiASiBSi=SiSiASiB((E)-2 and (Z)-2; SiA=t-BuMe2Si, SiB=i-Pr2MeSi) revealed the facile isomerization between(E)-2 and (Z)-2 with the activation free energy less than 15 kcal/mol at 303K; the value is ca. 10 kcal/mol smaller than those of E,Z-isomerization of other known stable disilenes with aryl or alkyl substituents. The origin of the low barrier for the silyl-substituted disilenes is ascribed to the the effective .SIGMA.-.PI. interaction at the transition state of the isomerization. At higher temperatures, isomerization of 2 to SiA2Si=SiSiB2 (3) was also observed. A similar facile E,Z-isomerization was observed between(E)- and (Z)-SiASiCSi=SiSiASiC(4; SiC=i-Pr3Si). Irradiation of disilene 4 gave a structural isomer SiA2Si=SiSiC2(5), which returned to 4 in the dark. (author abst.) |
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