University of Illinois Urbana-Champaign

New Chemistry of Transition Metal Alkyls and Hydrides: Bonding and Reactivity

Jefferis, Jesse M.

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Description

Title
New Chemistry of Transition Metal Alkyls and Hydrides: Bonding and Reactivity
Author(s)
Jefferis, Jesse M.
Issue Date
2000
Doctoral Committee Chair(s)
Girolami, Gregory S.
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2015-09-25T22:14:45Z
Keyword(s)
Chemistry, Inorganic
Language
eng
Abstract
Protonation of the osmium(II) hydrides (C5Me5)Os(PR 3)2H with tetrafluoroboric acid affords the corresponding osmium(IV) dihydride complexes of stoichiometry [(C5Me5)Os(PR 3)2H2+], where PR3 = PMe3, PEt3, PPh3, 1/2 dmpe, 1/2 dmpm, 1/2 dppm, or 1/2 dpdtm (where dmpe = 1,2-bis(dimethylphosphino)ethane, dmpm = bis(dimethylphosphino)methane, dppm = bis(diphenylphosphino)methane, and dpdtm = (diphenylphosphino)(di-p-tolylphosphino)methane. In the cisoid compounds [(C5Me5)Os(dmpm)H2 +] and [(C5Me5)Os(dppm)H2 +], the two hydride ligands undergo chemical exchange on the NMR time scale with activation free energies of 17.5 and 16.9 kcal mol-1 , respectively. Protonation of all the (C5Me5)Os(PR 3)2H complexes at low temperature affords the cisoid isomers, which must be the kinetic products. For the compounds [(C5Me 5)Os(PMe3)2H2+] and [(C5Me5)Os(PPh3)2H2 +], the cisoid isomers convert to the transoid isomers by two pathways, one unimolecular and one bimolecular; the latter involves intermolecular hydride exchange between the dihydride cations and the neutral monohydride.
Graduation Semester
2000
Type of Resource
text
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http://hdl.handle.net/2142/84483

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