Chemical activation of molecules by metals: Experimental studies of electron distributions and bonding
The formal relationship between measured molecular ionization energies and thermodynamic bond dissociation energies has been developed into a single equation which unifies the treatment of covalent bonds, ionic bonds, and partially ionic bonds. This relationship has been used to clarify the fundamental thermodynamic information relating to metal-hydrogen, metal-alkyl, and metal-metal bond energies. We have been able to obtain a direct observation and measurement of the stabilization energy provided by the agostic interaction of the C-H bond with the metal. The ionization energies have also been used to correlate the rates of carbonyl substitution reactions of ({eta}{sup 5}-C{sub 5}H{sub 4}X)Rh(CO){sub 2} complexes, and to reveal the electronic factors that control the stability of the transition state. The extent that the electronic features of these bonding interactions transfer to other chemical systems is being investigated in terms of the principle of additivity of ligand electronic effects. Specific examples under study include metal- phosphines, metal-halides, and metallocenes. Especially interesting has been the recent application of these techniques to the characterization of the soccer-ball shaped C{sub 60} molecule, buckminsterfullerene, and its interaction with a metal surface. The high-resolution valence ionizations in the gas phase reveal the high symmetry of the molecule, and studies of thin films of C{sub 60} reveal weak intermolecular interactions. Scanning tunneling and atomic force microscopy reveal the arrangement of spherical molecules on gold substrates, with significant delocalization of charge from the metal surface. 21 refs.
- Research Organization:
- Arizona State Univ., Tempe, AZ (United States). Dept. of Chemistry
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-86ER13501
- OSTI ID:
- 5093971
- Report Number(s):
- DOE/ER/13501-3; ON: DE92001988
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GERMANIUM HYDRIDES
CHEMICAL ACTIVATION
SILANES
AUGER ELECTRON SPECTROSCOPY
CARBONYLS
CYCLOPENTADIENE
DISSOCIATION ENERGY
ELECTRON TRANSFER
ELECTRONIC STRUCTURE
IONIZATION POTENTIAL
MANGANESE COMPLEXES
MOLYBDENUM COMPLEXES
NIOBIUM COMPLEXES
ORGANOMETALLIC COMPOUNDS
OSMIUM COMPLEXES
PHOSPHINES
PHOTOELECTRON SPECTROSCOPY
PROGRESS REPORT
RHENIUM COMPLEXES
RHODIUM COMPLEXES
ALKENES
COMPLEXES
CYCLOALKENES
DIENES
DOCUMENT TYPES
ELECTRON SPECTROSCOPY
ENERGY
GERMANIUM COMPOUNDS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHOSPHORUS COMPOUNDS
POLYENES
SILICON COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties