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

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Jew, Richard L.

Contributors dc:contributor

• Girolami, Gregory S.

• Chemistry, Inorganic

Language dc:language

eng

Identifier

(MiAaPQ)AAI3337810

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/84312