University of Illinois Urbana-Champaign

Steric and Electronic Effects Induced by Ancillary Ligand Substitutions on Cyclopentadienyl Osmium Complexes

Jew, Richard L.

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Description

Title
Steric and Electronic Effects Induced by Ancillary Ligand Substitutions on Cyclopentadienyl Osmium Complexes
Author(s)
Jew, Richard L.
Issue Date
2008
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
Keyword(s)
Chemistry, Inorganic
Language
eng
Abstract
To understand these variances, the molecular geometries of several osmium(II) and osmium(IV) complexes were investigated. (C5H5)Os(dmpm)Br reacts with NaOMe in refluxing methanol to afford the monohydride compound (C5H5)Os(dmpm)H, which can be protonated with HBF 4·Et2O to afford [(C5H5)Os(dmpm)H 2][BF4]. Comparison of the X-ray crystal structures of (C 5H5)Os(dmpm)H and (C5Me5)Os(dmpm)H revealed no significant differences. In contrast, comparison of the structures of [(C5H5)Os(dmpm)H2+] and [(C5Me5)Os(dmpm)H2+] showed that C5Me5 is more sterically demanding than C 5H5, as evidenced by the 7--8° decrease in the dihedral angle between the P-Os-P and C5 ring planes for the C5H 5 analogue, suggesting that movement of the phosphine toward the less sterically bulky C5 ring may lead to greater distances between cisoid ligands, effectively raising the barrier to hydrogen exchange in the dihydride and the methyl hydride systems.
Graduation Semester
2008
Type of Resource
text
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http://hdl.handle.net/2142/84312

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