Login

Publications  •  Project Statistics

Glossary  •  Schools  •  Disciplines
People Search: 
   
Title/Abstract Search: 

Dissertation Information for Travis M. Anderson

NAME:
- Travis M. Anderson

DEGREE:
- Ph.D.

DISCIPLINE:
- Chemistry

SCHOOL:
- Emory University (USA) (2002)

ADVISORS:
- Craig L. Hill

COMMITTEE MEMBERS:
- Michael C. Heaven
- Luigi G. Marzilli

MPACT Status: Fully Complete

Title: Metallation and isomerization effects of polyoxometalates on catalytic oxidation reactions

Abstract: In our attempts to synthesize new iron-containing Wells-Dawson polyoxometalates (POMs) for catalytic oxidation reactions, five new sandwich-type complexes have been prepared: ƒ¿ƒ¿ƒ¿ƒ¿-(NaOH 2 ) 2 Fe III 2 (P 2 W 15 O 56 ) 2 16- , ƒ¿ƒ¿ƒÀƒ¿-Cu II (OH 2 )Fe III 2 (P 2 W 15 O 56 )(P 2 (Cu II (OH 2 )) 2 W 13 O 52 ) 16- , ƒ¿ƒ¿ƒÀƒ¿-Co II (OH 2 )Fe III 2- (P 2 W 15 O 56 )(P 2 (Co II (OH 2 )) 2 W 13 O 52 ) 16- , ƒ¿ƒ¿ƒÀƒ¿-(Fe III OH 2 )(NaOH 2 )Fe III 2- (P 2 W 15 O 56 ) 2 14- , and ƒ¿ƒÀƒÀƒ¿-(Ni II OH 2 ) 2 Fe III 2 (P 2 W 15 O 56 ) 2 14- . These complexes were characterized by X-ray crystallography, 31 P NMR, IR, and elemental analysis. The complexes have been converted to tetra- n -butylammonium salts by a metathesis reaction and were used for the oxidation of alkenes by H 2 O 2 . ƒ¿ƒ¿ƒ¿ƒ¿-(NaOH 2 ) 2 Fe III 2 (P 2 W 15 O 56 ) 2 16- and ƒ¿ƒÀƒÀƒ¿-(Ni II OH 2 ) 2 Fe III 2 (P 2 W 15 O 56 ) 2 14- were the most effective catalysts, each giving more than 200 turnovers of epoxide (for the oxidation of cyclooctene) over a 40 hour period with more than 98% selectivity.

Reaction of ƒ¿-P 2 W 15 O 56 12- and Fe(III) in a saturated NaCl solution produces the first trisubstituted Wells-Dawson structure with three low-valent (non-d 0 ) metals, ƒ¿-(Fe III Cl) 2 (Fe III OH 2 )P 2 W 15 O 59 11- . Dissolution of this species into 1 M NaBr gives the triaquated species ƒ¿-(Fe III OH 2 ) 3 P 2 W 15 O 59 9- .Ionic strength values of 1 M or greater are necessary to avoid decomposition of these speciesto the conventional sandwich-type complex, ƒ¿ƒÀƒÀƒ¿-(Fe III OH 2 ) 2 Fe III 2 (P 2 W 15 O 56 ) 2 12- .

Finally, to further understand the role Baker-Figgis isomerization plays on the overall stability of POM structures (including the sandwich-type POMs), a quantitative kinetic, thermodynamic, and mechanistic study was undertaken which may also be a model for the related metal oxide systems. The isomerization of ƒÀ-P 2 W 18 O 62 6- to ƒ¿-P 2 W 18 O 62 6- , followed by 31 P NMR, has a bimolecular rate constant of 9.3 ~ 10 -1 M -1 s -1 at 343K in pH = 4.24 acetate buffer. A mechanism is proposed involving the formation of a defect complex (missing one or more W centers) followed by isomerization and reconstitution of the parent structure.

MPACT Scores for Travis M. Anderson

A = 0
C = 0
A+C = 0
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-03-23 20:48:47

Advisors and Advisees Graph