Physical Organic Chemistry of Transition Metal Carbene Complexes. 16.1 Reactions of (CO)5MC(OR)Ph (M = Cr or W; R = Me or Et) with Thiolate Ions in Aqueous Acetonitrile. Complete Kinetic Dissection of the Two-Step Mechanism
| Autor: | Francis X. Flores, Claude F. Bernasconi, Kevin W. Kittredge |
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| Rok vydání: | 1999 |
| Předmět: |
Nucleophilic addition
Chemistry Inorganic chemistry General Chemistry Biochemistry Medicinal chemistry Catalysis chemistry.chemical_compound Colloid and Surface Chemistry Reaction rate constant Nucleophile Tetrahedral carbonyl addition compound Nucleophilic substitution Physical organic chemistry Carbene Equilibrium constant |
| Zdroj: | Journal of the American Chemical Society. 121:6630-6639 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | A kinetic study of the reactions of (CO)5MC(OR‘)Ph (1a, M = Cr, R‘ = Me; 1b, M = W, R‘ = Me; 1c, M = Cr, R‘ = Et; 1d, M = W, R‘ = Et) with n-PrS-, HOCH2CH2S-, MeO2CCH2CH2S-, and MeO2CCH2S- in 50% MeCN−50% water (v/v) at 25 °C is reported. At low [RS-] and relatively low pH the reaction leads to the nucleophilic substitution products (CO)5MC(SR)Ph without accumulation of any intermediate. At high [RS-] and high pH formation of a tetrahedral intermediate, (CO)5MC(OR‘)(SR)Ph, is observed. Upon addition of acid the intermediate is converted into the substitution product. For the reactions of most thiolate ions a detailed kinetic analysis allowed the determination of the rate constants for nucleophilic attack on the carbene complexes (k1) and its reverse (k-1), the equilibrium constant for nucleophilic addition (K1 = k1/k-1), and the rate constants for alkoxide ion departure from the respective intermediates catalyzed by H+ ( ) and N-methylmorpholinium ion ( ). The dependence of these rate and equilibrium con... |
| Databáze: | OpenAIRE |
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