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Nucleophilic Activation of Carbon Monoxide: Synthesis, Characterization and Reactivity of Intramolecular Group VI Metallaesters

Citation

Coolbaugh, Thomas Smith (1985) Nucleophilic Activation of Carbon Monoxide: Synthesis, Characterization and Reactivity of Intramolecular Group VI Metallaesters. Dissertation (Ph.D.), California Institute of Technology. https://resolver.caltech.edu/CaltechTHESIS:12172018-123100783

Abstract

An investigation of the design and reactivity of bifunctional transition metal complexes pertinent to homogeneous reduction of carbon monoxide is presented. Oxygen nucleophiles were incorporated into Group VI metal carbonyl complexes via cyclopentadienyl ligands.

Neutral molybdenum dimers yield no intramolecular nucleophilic interaction between an alcohol, attached by different bridging arm lengths, and the metal carbonyl fragment. A crystal structure of the propanol substituted cyclopentadienyl molybdenum tricarbonyl dimer (space group P1, a = 7.487 Å, b = 7.713 Å, c = 10.902 Å, α = 99.3600°, β = 81.460°, γ = 115.260°, V = 563.0 Å3, Z = 1) indicates only an intermolecular hydrogen bond between alcohols.

The synthesis of the cationic compounds, [CpRM(CO)3L]+BF-4 is reported, where M = Mo, W and R = -(CH2)η - OH with n = 1-3. Deprotonation of the alcohols leads to intramolecular metallaester formation for the methylene and ethylene bridged compounds. The equilibria established upon reaction with external alcohols are reported as are the thermodynamic parameters associated with the process.

Crystal structures of the metallaesters bridged by a methylene (space group P21/n, a = 7.867 Å, b = 17.083 Å, c = 17.768 Å, β= 100.959°, V = 2344.4 Å3, Z = 4) and ethylene group (space group P21/n, a = 8.127 Å, b = 16.823 Å, c = 17.623 Å, β = 101.980°, V = 2357.1 Å3, Z = 4) are presented. A comparison of the structures is given.

Reaction of the intramolecular metallaesters with molecular hydrogen produces no volatile products. Reaction with stoichiometric hydride sources yields compounds of relevance to carbon monoxide reduction. Reactions with Me+ and water are presented, the latter giving rise to a stoichiometric analog of the water-gas shift reaction.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Bercaw, John E. (advisor)
  • Grubbs, Robert H. (co-advisor)
Thesis Committee:
  • Grubbs, Robert H. (chair)
  • Schaefer, William P.
  • Dougherty, Dennis A.
  • Bercaw, John E.
Defense Date:20 June 1984
Record Number:CaltechTHESIS:12172018-123100783
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:12172018-123100783
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11319
Collection:CaltechTHESIS
Deposited By: Lisa Fischelis
Deposited On:19 Dec 2018 17:46
Last Modified:02 Dec 2020 01:33

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