Download Synthesis and Characterization of a Copper(I)

Progress Towards the Synthesis and Characterization of a Copper(I)-Phenyl Complex
Thabiso Kunene; Thora Maltais (‘09), Mark Ziffer (’11), Rebecca Conry
Department of Chemistry, Colby College, Waterville, ME, USA
INTRODUCTION
•
•
•
•
A complex consists of a central metal, bonded to a surrounding
group of molecules or atoms called ligands. The ligands often
bind the metal through atoms such as carbon, oxygen, or
nitrogen.
Numerous complexes occur naturally, for instance hemocyanins,
which are proteins that carry oxygen in the bodies of some
invertebrate animals such as lobsters.
Organometallic complexes have metal-carbon bonds
Organometallic complexes of copper are some of the most widely
used reagents in synthetic organic chemistry, such as for adding
an alkyl group to an acid chloride.
•
However, most organocopper complexes are formed and used
without being isolated so their chemistry is underdeveloped,
including that for copper-arene complexes.
•
Only a few copper(I)-arene complexes have been reported, for
most of these, the copper(I) ion only interacts with the arene in
the solid state, not in solution.
We are continuing previous work in which the first
Cu(I)-naphthyl complex (Figure 1) was synthesized, isolated, and
shown to bind the arene group both in solution and in the solid
state.
•
MATERIALS and METHODS
Ligand synthesis step 1
Ligand synthesis step 4
Compound 1 is formed by substituting the three Hs in diethanolamine
with Ts from p-toluenesulfonic acid (TsCl). The resultant OTs is a better
leaving group than OH to aid the synthesis of compound 2 in step 2.
This step adds the ethyl phenyl arm
Ligand synthesis step 2
Synthesis of complex
The cyclic compound 2 is made by replacing the OTs groups with the
sulfur groups from 1,3-propanedithiol to form a ring.
Benzene copper triflate will be used as a source of Cu(I) to try to form the target Cu(I)-phenyl
complex labeled 5 below.
Note:
Even though a binding Cu-arene site is indicated, it has not yet been definitely determined.
RESULTS and FUTURE DIRECTIONS
Ligand synthesis step 3
• Compounds 1, 2, and 3 have been synthesized
• Our manipulative, analytical, chemical reasoning skills and understanding has greatly
improved through handling and preparation of these compounds.
Compound 3 is formed upon exchanging the Ts group with H, so that the
H can be replaced with an ethyl phenyl arm in step 4.
•
•
•
This project aims to synthesize and characterize a Cu(I)-phenyl
complex in order to probe the factors that contribute to the
strength and selectivity of the copper-phenyl bond. The target
complex (Figure 2) requires five synthetic steps, four to make the
ligand plus another to make the complex.
•
Upon synthesis of the Cu(I)-phenyl complex, nuclear magnetic resonance (NMR) will be
used to study the Cu(I)-phenyl binding ability and binding location.
An attempt to grow crystals of the Cu(I)-phenyl complex will be made so that X-ray
crystallography can be used to study the Cu(I)-phenyl binding in the solid state.
The results will then be compared with those from Max Cushner’s work in order to better
understand Cu(I)-arene complexes.
CITATIONS
ACKNOWLEDGEMENTS
1. Conry, R. R.; Striejewske, W. S.; Tipton, A. A. Inorganic Chemistry 1999, 38, 2833-2843
2. Conry, R. R.; Tipton, A. A.; Striejewske, W. S.; Erkizia, E.; Malwitz, M. A.; Caffaratti, A.; Natkin, J. A. Organometallics 2004, 23, 5210
3. Chandrasekar, S.; McAuley, A. Inorganic. Chemistry. 1992, 31, 2234-2240
•
•
•
•
Colby College and Colby College Science Division
Thora Maltais (‘09), Mark Ziffer (‘11), and Alex Tipton for previous results
Max Cushner
ACS-PRF