Organo-f-element thermochemistry. Metal-ligand bond disruption enthalpies in (pentamethylcyclopentadienyl)thorium hydrocarbyls, metallacycles, hydrides, and dialkylamides
Journal Article
·
· J. Am. Chem. Soc.; (United States)
Thorium-ligand bond disruption enthalpies (D) have been determined in the series Cp'/sub 2/Th(thorium)R/sub 2/ (Cp' = eta/sup 5/-(pentamethylcyclo-pentadienyl-(CH/sub 3/)/sub 5/C/sub 5/) for a range of R groups including R = 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 to 90 kcal/mol, with C/sub 6/H/sub 5/ > CHa3 approx. = CH/sub 2/Si(CH/sub 3/)/sub 3/ > CH/sub 2/CH/sub 3/ greater than or equal to CH/sub 2/C/sub 6/H/sub 5/ approx. = n-C/sub 4/H/sub 9/ approx. = CH/sub 2/C(CH/sub 3/)/sub 3/. Th-C bonds appear to be strengthened by ThOR coligands and possibly weakened by Th-Cl coligands. The strain energies in thoracyclobutanes Cp'/sub 2/Th(CH/sub 2/)/sub 2/C(CH/sub 3/)/sub 2/ and Cp'/sub 2/Th(CH/sub 2/)/sub 2/Si(CH/sub 3/)/sub 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/sub 2/ bond is ca. 18 kcal/mol stronger. These data afford a considerably expanded understanding of organoactinide reaction patterns involving C-H activation, ..beta..-hydride elimination, and CO insertion as well as why they sometimes differ from those of middle and late first-row transition elements. 3 figures, 2 tables.
- Research Organization:
- Argonne National Lab., IL
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5557460
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:23; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPLEXES
ACTINIDE COMPOUNDS
ALCOHOLS
ALKANES
ANAEROBIC CONDITIONS
AROMATICS
BINDING ENERGY
BUTANOLS
CALORIMETRY
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
COMPLEXES
DATA
ENERGY
ENTHALPY
EXPERIMENTAL DATA
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
LIGANDS
MEDIUM TEMPERATURE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PHYSICAL PROPERTIES
REACTION HEAT
SAMPLE PREPARATION
SILANES
SILICON COMPOUNDS
SOLUTION HEAT
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
THORIUM COMPLEXES
THORIUM COMPOUNDS
THORIUM HYDRIDES
TITRATION
TOLUENE
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPLEXES
ACTINIDE COMPOUNDS
ALCOHOLS
ALKANES
ANAEROBIC CONDITIONS
AROMATICS
BINDING ENERGY
BUTANOLS
CALORIMETRY
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
COMPLEXES
DATA
ENERGY
ENTHALPY
EXPERIMENTAL DATA
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
LIGANDS
MEDIUM TEMPERATURE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PHYSICAL PROPERTIES
REACTION HEAT
SAMPLE PREPARATION
SILANES
SILICON COMPOUNDS
SOLUTION HEAT
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
THORIUM COMPLEXES
THORIUM COMPOUNDS
THORIUM HYDRIDES
TITRATION
TOLUENE