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Introduction
Investigating heavy, group 15 elements reveals interesting chemical reactivity and catalytic potential
The Johnstone Lab has successfully isolated a monomeric stibine oxide
My project builds off this discovery by accessing new reactivity at the stiboryl group via chemistry across the stibine-oxygen bond
Figure 1: The crystal structure of a monomeric stibine oxide where the unsaturated Sb=O bond is protected by sterically bulky Dipp (2,6-diisopropylphenyl) groups
Figure 2: The isolation of trimesitylstibine oxide where the stibroyl group is kinetically shielded by the mesityl groups
This project works with trimesityl stibine oxide, which is less sterically encumbered than the previously isolated tris(diisopropylphenyl)stibine oxide
The highly reactive nature of trimesityl groups allows it to engage in interesting reactivity
This project will deepen our understanding of the bonding and reactivity of antimony
Syntheses
A series of air and water-sensitive reactions were carried out in the Glovebox
These techniques were employed to prevent immediate hydrolysis to form the Dihydroxy stiborane
Each synthetic step shows the addition of a diverse array of carboxylate groups resulting from the cleavage of a starting anhydride.
The 1,2 addition occurs across the unsaturated stibine-oxygen bond
Figure 3: Trimesitylstibine oxide was reacted with acetic anhydride to form diacetatotrimesitylstiborane
Figure 4: Trimesitylstibine oxide was reacted with di-tert-butyl dicarbonate to form ditertbutylcarbonatotrimesitylstiborane
Figure 5: Trimesitylstibine oxide was reacted with trifluoroacetic anhydride to form bis(trifluoroacetato)trimesitylstiborane
Crystallographic Data
The structure of the diacetato trimesitylstiborane was confirmed by X-ray crystallography
Shows the Sb as trigonal bipyramidal with the mesityl groups at equatorial positions and the acetate groups at axial positions
Significance
Demonstrated new reactivity across the antimony-oxygen bond that can be evaluated for catalytic potential
Outlined new mechanisms to add anhydrides across the antimony-oxygen bond
Reported the structures of three novel antimony compounds
Can compare reactivity to further understanding of group 15 elements
Future Directions
Obtain crystallographic data for ditertbutylcarbonatotrimesitylstiborane and bis(trifluoroacetato)trimesitylstiborane
Attempt synthesis with trifluoromethanesulfonic anhydride
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