Synthesis and Reactivity of Oxorhenium(V) Methyl, Benzyl, and Phenyl Complexes with CO: Implications for a Unique Mechanism for Migratory Insertion
| Autor: | Leanna K. Robbins, Elon A. Ison, Paul D. Boyle, Cassandra P. Lilly, Jessica L. Smeltz |
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| Rok vydání: | 2015 |
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| Zdroj: | Organometallics. 34:3152-3158 |
| ISSN: | 1520-6041 0276-7333 |
| Popis: | The complexes [(DAAm)Re(O)(R)] [DAAm = N,N-bis(2-arylaminoethyl)methylamine; aryl = C6F5], 1, R = Me; 3a–d (R = benzyl, a; 4-methylbenzyl, b; 4-fluorobenzyl, c; 4-methoxybenzyl, d); and 4, R = Ph, were synthesized. CO insertion into the Re–R bond in 1 and 3a–d resulted in the formation of the acetyl complex, 2, and the (aryl)acetyl complexes, 5a–d respectively. The formation of 5a–d proceeded at a faster rate (7 h) than the formation of 2 (72 h) under the same conditions. No reaction was observed however for the phenyl complex 4 with CO. Kinetics for CO insertion into the various Re–R bonds were examined, and the experimental rate law was determined to be Rate = kobs[Re][CO]. The activation parameters for CO insertion into 1 and 3a were determined to be ΔG⧧(298 K) = 24(1). The enthalpy of activation ΔH⧧ was determined to be 9(1) and 10(3) kcal/mol for 1 and 3a, respectively, and the entropy of activation, ΔS⧧, was −49(2) and −36(4) cal/mol·K. Computational studies (M06) are consistent with the hypothesis ... |
| Databáze: | OpenAIRE |
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