ORGANO-f-ELEMENT THERMOCHEMISTRY. METAL-LIGAND BOND DISRUPTION ENTHALPIES IN (PENTAMETHYLCYCLOPENTADIENYL)THORIUM HYDROCARBYLS, METALLACYCLES, HYDRIDES, AND DIALKYLAMIDES.

Joseph W. Bruno, Tobin J Marks, Lester R. Morss

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Abstract

Thorium-ligand bond disruption enthalpies (D) have been determined in the series Cp prime //2ThR//2(Cp prime equals eta **5 minus (CH//3)//5C//5) for a range of R groups including R equals alkyl, aryl, metallacycle, hydride, and dialkylamide. Enthalpy data were obtained in an anaerobic batch-titration isoperibol reaction calorimeter from heats of solution in toluene followed by heats of alcoholysis with tert-butyl alcohol. Calculated Th-hydrocarbyl bond disruption enthalpies fall in the range 60-90 kcal/mol, with C//6H//5 greater than CH//3 approximately equals CH//2Si(CH//3)//3 greater than CH//2CH//3 greater than equivalent to CH//2C//6H//5 approximately equals n-C//4H//9 approximately equals CH//2C(CH//3)//3. Th-C bonds appear to be strengthened by ThOR coligands and possibly weakened by Th-Cl coligands. The strain energies in thoracyclobutanes Cp prime //2Th(CH//2)//2C(CH//3)//2 and Cp prime //2Th(CH//2)//2Si(CH//3)//2 are estimated to be ca. 16 and 8 kcal/mol, respectively. A Th-H bond is ca. 20 kcal/mol stronger than a Th-alkyl bond, while a Th-NR//2 bond is ca. 18 kcal/mol stronger.

Original languageEnglish
Pages (from-to)6824-6832
Number of pages9
JournalJournal of the American Chemical Society
Volume105
Issue number23
Publication statusPublished - Jan 1 1983

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Thorium
Thermochemistry
Hydrides
Chemical elements
Enthalpy
Hot Temperature
Metals
Ligands
tert-Butyl Alcohol
Toluene
Strain energy
Calorimeters
Titration
Alcohols

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "ORGANO-f-ELEMENT THERMOCHEMISTRY. METAL-LIGAND BOND DISRUPTION ENTHALPIES IN (PENTAMETHYLCYCLOPENTADIENYL)THORIUM HYDROCARBYLS, METALLACYCLES, HYDRIDES, AND DIALKYLAMIDES.",
abstract = "Thorium-ligand bond disruption enthalpies (D) have been determined in the series Cp prime //2ThR//2(Cp prime equals eta **5 minus (CH//3)//5C//5) for a range of R groups including R equals alkyl, aryl, metallacycle, hydride, and dialkylamide. Enthalpy data were obtained in an anaerobic batch-titration isoperibol reaction calorimeter from heats of solution in toluene followed by heats of alcoholysis with tert-butyl alcohol. Calculated Th-hydrocarbyl bond disruption enthalpies fall in the range 60-90 kcal/mol, with C//6H//5 greater than CH//3 approximately equals CH//2Si(CH//3)//3 greater than CH//2CH//3 greater than equivalent to CH//2C//6H//5 approximately equals n-C//4H//9 approximately equals CH//2C(CH//3)//3. Th-C bonds appear to be strengthened by ThOR coligands and possibly weakened by Th-Cl coligands. The strain energies in thoracyclobutanes Cp prime //2Th(CH//2)//2C(CH//3)//2 and Cp prime //2Th(CH//2)//2Si(CH//3)//2 are estimated to be ca. 16 and 8 kcal/mol, respectively. A Th-H bond is ca. 20 kcal/mol stronger than a Th-alkyl bond, while a Th-NR//2 bond is ca. 18 kcal/mol stronger.",
author = "Bruno, {Joseph W.} and Marks, {Tobin J} and Morss, {Lester R.}",
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N2 - Thorium-ligand bond disruption enthalpies (D) have been determined in the series Cp prime //2ThR//2(Cp prime equals eta **5 minus (CH//3)//5C//5) for a range of R groups including R equals alkyl, aryl, metallacycle, hydride, and dialkylamide. Enthalpy data were obtained in an anaerobic batch-titration isoperibol reaction calorimeter from heats of solution in toluene followed by heats of alcoholysis with tert-butyl alcohol. Calculated Th-hydrocarbyl bond disruption enthalpies fall in the range 60-90 kcal/mol, with C//6H//5 greater than CH//3 approximately equals CH//2Si(CH//3)//3 greater than CH//2CH//3 greater than equivalent to CH//2C//6H//5 approximately equals n-C//4H//9 approximately equals CH//2C(CH//3)//3. Th-C bonds appear to be strengthened by ThOR coligands and possibly weakened by Th-Cl coligands. The strain energies in thoracyclobutanes Cp prime //2Th(CH//2)//2C(CH//3)//2 and Cp prime //2Th(CH//2)//2Si(CH//3)//2 are estimated to be ca. 16 and 8 kcal/mol, respectively. A Th-H bond is ca. 20 kcal/mol stronger than a Th-alkyl bond, while a Th-NR//2 bond is ca. 18 kcal/mol stronger.

AB - Thorium-ligand bond disruption enthalpies (D) have been determined in the series Cp prime //2ThR//2(Cp prime equals eta **5 minus (CH//3)//5C//5) for a range of R groups including R equals alkyl, aryl, metallacycle, hydride, and dialkylamide. Enthalpy data were obtained in an anaerobic batch-titration isoperibol reaction calorimeter from heats of solution in toluene followed by heats of alcoholysis with tert-butyl alcohol. Calculated Th-hydrocarbyl bond disruption enthalpies fall in the range 60-90 kcal/mol, with C//6H//5 greater than CH//3 approximately equals CH//2Si(CH//3)//3 greater than CH//2CH//3 greater than equivalent to CH//2C//6H//5 approximately equals n-C//4H//9 approximately equals CH//2C(CH//3)//3. Th-C bonds appear to be strengthened by ThOR coligands and possibly weakened by Th-Cl coligands. The strain energies in thoracyclobutanes Cp prime //2Th(CH//2)//2C(CH//3)//2 and Cp prime //2Th(CH//2)//2Si(CH//3)//2 are estimated to be ca. 16 and 8 kcal/mol, respectively. A Th-H bond is ca. 20 kcal/mol stronger than a Th-alkyl bond, while a Th-NR//2 bond is ca. 18 kcal/mol stronger.

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