University of Illinois Urbana-Champaign

Synthesis and reactivity of osmium-chromium oxidation catalysts and routes to a chiral analog

Allen, Jana Leanne

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Description

Title
Synthesis and reactivity of osmium-chromium oxidation catalysts and routes to a chiral analog
Author(s)
Allen, Jana Leanne
Issue Date
1996
Doctoral Committee Chair(s)
Shapley, Patricia A.
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
  • Chemistry, Organic
Language
eng
Abstract
  • Osmium-chromium heterobimetallic complexes of the type (Y) (M(N)$\rm R\sb2(\mu$-O)$\rm\sb2CrO\sb2$) (Y = NBu$\sb4$, PPh$\sb4$; M = Os, Ru; R = Me, CH$\rm\sb2SiMe\sb3$, C$\rm\sb6H\sb5$) act as catalysts for the oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones using dioxygen as the secondary oxidant. These complexes also catalyze the oxidation of 1,2-bis(diphenylphosphino)ethane (dppe) to the corresponding phosphine oxide, Ph$\sb2$P(O)CH$\rm\sb2CH\sb2P(O)Ph\sb2$. None of the singly oxidized phosphine is detected. Investigations into the kinetics of the oxidation reactions showed the oxidation of benzyl alcohol to benzaldehyde is first order in both alcohol and catalyst concentration. A mechanism involving coordination of the alcohol to the osmium center, followed by proton transfer and $\beta$-hydrogen elimination of the products yields a reduced osmium-chromium complex. This reduced complex can react with dioxygen to form a bridging peroxo complex that can react with a molecule of the reduced complex to regenerate two equivalents of the original heterobimetallic complex. Dioxygen labeling studies in the oxidation of dppe are described. Based on these experiments, two potential mechanisms are proposed for the oxidation of dppe. Routes toward the synthesis of a chiral version of the heterobimetallic catalyst utilizing a chiral counterion or an alkyl group derived from S-2-methylbutane, 2,2$\sp\prime$-dimethylbinaphthyl, camphene, 9,10-dibromocamphor and 2-norbornane are described.
  • The synthesis of several new inorganic and organometallic compounds of osmium are described: (PPh$\rm\sb4\rbrack\lbrack Os(N)(CH\sb2SiMe\sb3)\sb2(\mu$-O)$\rm\sb2CrO\sb2\rbrack,$ trans- (PPh$\rm\sb4\rbrack\lbrack Os(N)(CH\sb2SiMe \sb3)\sb2Br\sb2$), (N(n-Bu)$\rm\sb4\rbrack\lbrack Os(N)(C\sb6H\sb5)\sb4$), (N(n-Bu)$\rm\sb4\rbrack\lbrack Os(N)(C\sb6H\sb5)\sb2Cl\sb2\rbrack,\ Os(N)(C\sb6H\sb5)\sb3$(py), (N(n-Bu)$\rm\sb4\rbrack\lbrack Os(N)(C\sb6H\sb5)\sb2(\mu$-O)$\rm\sb2CrO\sb2$), (PPh$\rm\sb4\rbrack\lbrack Os(N)(CH\sb2SiMe\sb3)\sb2(dppe)(O$-CrO$ \sb3$)), (N(n-Bu)$\rm\sb4\rbrack\lbrack Os(N)(CH\sb2SiMe\sb3)\sb2(dppe)(O$-CrO$\rm\sb3$)), (N(n-Bu)$\rm\sb4\rbrack\lbrack Os(N)(CH\sb2SiMe\sb3)\sb2(dppe)(O$-SO$\rm\sb3$)), ((R)-PhCH(Me)NMe$\rm\sb3\rbrack\lbrack Os(N)Cl\sb4$), ((R)-PhCH(Me)NMe$\rm\sb3\rbrack\lbrack Os(N)(OSiMe\sb3)\sb4$), ((R)-PhCH(Me)NMe$\rm\sb3\rbrack\lbrack Os(N)(CH\sb3)\sb4\rbrack,\ \lbrack PPh\sb4\rbrack\lbrack Os(N)(CH\sb2SiMe\sb3)\sb3Br\rbrack.$
Type of Resource
text
Permalink
http://hdl.handle.net/2142/20502
Copyright and License Information
Copyright 1996 Allen, Jana Leanne

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