Current time in Korea 12:34 Sep 23 (Mon) Year 2019 KCS KCS Publications
KCS Publications
My Journal Log In Register
HOME > Search > Browsing(BKCS) > Archives

Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 14, Number 2
BKCSDE 14(2)
February 20, 1993 

 
Title
Kinetics and Stereochemistry of CO Substitution Reactions of Half-Open Chromocene Carbonyls(Ⅰ) : Reactions of Cp(C5H7)CrCO and Phosphines
Author
Jong-Jae Chung*, Byung-Gill Roh, Yu-Chul Park
Keywords
Abstract
The CO substitution reactions in the complex, Cp(S-C5H7)CrCO with PR3(PR3=PMePh2, P(OCH3)3, PMe2Ph) were investigated spectrophotometrically at various temperatures. From the reaction rates, it was suggested that the CO substitution reaction takes place by first-order (dissociative) pathway. Activation parameters in decaline are △H≠=24.58 kcal· mol-1, △S≠=3.05 cal·mol-1·K-1. Unusually low value of △S≠ suggests an η5-S→η5-U conversion of the pentadienyl ligand. This was confirmed by the extended-Huckel molecular orbital (EHMO) calculations, which revealed that the total energy Of Cp(S-C5H7)CrCO is about 6.84 kcal/mol more stable than that of Cp(U-C5H7)CrCO and the energy Of [Cp(U-C5H7)Cr]≠ transition state is about 4.25 kcal/mol lower than that of [Cp(S-C5H7)Cr]≠ transition state.
Page
207 - 211
Full Text
PDF