Research in the
Waterman Group addresses problems in synthesis, catalysis, materials, and energy through the
application of organometallic systems. These efforts are directed at
the discovery of new synthetic methods in the main group, the
preparation of novel materials, and development of efficient or "green"
syntheses through catalysis.
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| I. BOND-FORMING
CATALYSIS |
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We
have been investigating methods to catalytically form bonds between
main group elements. In particular, we have been looking at generating
bonds to phosphorus. There is a rich synthetic chemistry associated
with phosphorus; however, methods to generate those bonds catalytically
are sparse.
To
meet this end, we are applying early transition-metal complexes in
dehydrocoupling reactions. Dehydrocoupling catalysis effectively
exchanges element-hydrogen bonds from two
molecules
to form an element-element bond with
liberation of hydrogen. We have recently demonstrated that
triamidoamine complexes of zirconium are effective catalysts for the
dehydrocoupling of phosphines. Further, we found that the catalysis
appears to rely on sigma-bond metathesis steps for P–P bond formation (right).
Applying this knowledge, we have already demonstrated selective P–Si and P–Ge bond-forming catalysis.
Our
main goal in developing these new methods
is to use this kind of catalysis in the synthesis of novel materials
that may exhibit unique properties. |
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| II. CHEMICAL STORAGE OF HYDROGEN |
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Simple main-group molecules are being considered as
method to storing hydrogen because of the inherent difficulties
associated with pressurization, liquefaction, and physisorption. We are
applying our knowledge of dehydrocoupling catalysis to develop an
understanding of how hydrogen released from simple inorganic molecules
such as amine-boranes with the broader goal of developing strategies to
reversibly liberate hydrogen from these molecules. |
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| III. SYNTHESIS INVOLVING
LOW-VALENT FRAGMENTS |
| Another route we are exploring to
forming element–element bonds
is through the generation of low-valent fragments. Molecular
precursors to low valent fragments are known for lighter elements such
as carbon or nitrogen. This is not true for the heavier main-group
elements. We have been investigating alpha-elimination,
or the
extrusion of a low-valent fragment from a transition-metal, as one
possible route to these kind of species. Recently, we have discovered
the first instance of catalytic alpha-arsinidene elimination. |
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| We are
also interested in discovering innovative
routes to accessing low-valent main-group fragments. A recent
development in this area is our preparation of a phosphaalkene
(molecule with a P=C bond) by
insertion of an isocyanide into a zirconium-phosphorus bond. In this
reaction, we take a commercially available phosphorus source, a primary
phosphine, and effectively access a phosphinidene ("PR") fragment with
perfect
atom economy. |
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Our triamidoamine complexes
have been incredibly successful thus far. We expect that the reactivity
of these species can be tuned by alterations to the supporting ligand.
Thus, we seek to improve desired properties and reactivity by changing
the ligand system. We have begun a collaboration with Professor Cora
MacBeth at
Emory University as part of these
efforts.
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Research in the Waterman Group is generously supported by a number of agencies through grants and awards.
-U. S. National Science Foundtion (grant number CHE-0747612)
-Research Corporation for Science Advancement through a Cottrell Scholar Award to R. W.
-Alfred P. Solan Foundation through a Research Fellowship to R. W.
-American Chemical Society Petroleum Research Fund (grant number 466669-G3)
-Vermont Space Grant Consortium (Graduate Research Assistantship for Analese Maddox)
-Project SEED (summer funding for high school students)
-Univerity of Vermont (start-up funds) |
Last modified June 8, 2009 05:25
AM
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