Thermodynamic, Kinetic, Structural, and Computational Studies of the Ph3Sn–H, Ph3Sn–SnPh3, and Ph3Sn–Cr(CO)3C5Me5 Bond Dissociation Enthalpies
| Autor: | Xiaochen Cai, Burjor Captain, Anjaneyulu Koppaka, Manuel Temprado, Leonardo F. Serafim, George C. Fortman, Carl D. Hoff, Subhojit Majumdar |
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| Rok vydání: | 2016 |
| Předmět: |
010405 organic chemistry
Chemistry Kinetics Enthalpy Hydrogen atom 010402 general chemistry 01 natural sciences Bond-dissociation energy Toluene Dissociation (chemistry) 0104 chemical sciences Inorganic Chemistry chemistry.chemical_compound Reaction calorimeter Kinetic isotope effect Physical chemistry Physical and Theoretical Chemistry |
| Zdroj: | Inorganic Chemistry. 55:10751-10766 |
| ISSN: | 1520-510X 0020-1669 |
| Popis: | The kinetics of the reaction of Ph3SnH with excess •Cr(CO)3C5Me5 = •Cr, producing HCr and Ph3Sn–Cr, was studied in toluene solution under 2–3 atm CO pressure in the temperature range of 17–43.5 °C. It was found to obey the rate equation d[Ph3Sn–Cr]/dt = k[Ph3SnH][•Cr] and exhibit a normal kinetic isotope effect (kH/kD = 1.12 ± 0.04). Variable-temperature studies yielded ΔH‡ = 15.7 ± 1.5 kcal/mol and ΔS‡ = −11 ± 5 cal/(mol·K) for the reaction. These data are interpreted in terms of a two-step mechanism involving a thermodynamically uphill hydrogen atom transfer (HAT) producing Ph3Sn• and HCr, followed by rapid trapping of Ph3Sn• by excess •Cr to produce Ph3Sn–Cr. Assuming an overbarrier of 2 ± 1 kcal/mol in the HAT step leads to a derived value of 76.0 ± 3.0 kcal/mol for the Ph3Sn–H bond dissociation enthalpy (BDE) in toluene solution. The reaction enthalpy of Ph3SnH with excess •Cr was measured by reaction calorimetry in toluene solution, and a value of the Sn–Cr BDE in Ph3Sn-Cr of 50.4 ± 3.5 kcal/mol was... |
| Databáze: | OpenAIRE |
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