Reports: B3
43649-B3 Copper(I)-Arene Binding Studies with New Aryl-Appended Macrocyclic Ligands
This grant is supporting efforts by undergraduate students to explore new Cu(I)-arene complexes. Thus, we wish to extend previously reported results by my group demonstrating copper(I)-arene binding in the copper complex of the ligand (N-ethyl-1-naphthyl)-1-aza-4,8-dithiacyclodecane. In that complex, the pendant naphthyl group coordinates in an η2-mode to the copper(I) ion in both the solid state and solution. To more fully understand the preferences of copper(I)-arene binding, we are synthesizing and characterizing new aryl-appended macrocylic ligands and copper(I) complexes of those ligands.
Our results thus far include the five-step preparation of the naphthyl-appended macrocyclic ligand [(N-ethyl-2-naphthyl)-1-aza-4,8-dithiacyclodecane, 2-napL], which is a structural isomer of the ligand used in the reported complex described above. We have also successfully prepared the phenyl-appended analogous ligand (PhL) in four steps. Copper(I) complexes with these macrocyclic ligands and an acetonitrile or triphenylphosphine ancillary ligand have been prepared. These non-arene complexes are partially characterized at this point and should be fully characterized in the near future. The characterizational data for these complexes will help us more confidently assign spectra of any Cu(I)-arene complexes with the same ligands (PhL and 2-napL). Thus, we will be able to more clearly tell if Cu(I)-arene binding occurs and to which positions in the arene ring binding occurs when it does. We are also planning to make [2-napLCu]+ and [PhLCu]+ soon in order to probe these complexes for Cu(I)-arene interactions in solution by NMR and UV-vis spectroscopies as well as in the solid state by X-ray diffraction. A journal article containing results from those experiments combined with those for the copper(I)-acetonitrile and -triphenylphosphine complexes will then be written up and submitted.
Kathryn (Kate) Sherry and Thora Maltais worked part-time on this project during the 2008-2009 academic year for credit (Colby College has a policy that students either earn academic credit or money, but not both). This was Thora's senior year (she is now a first-year chemistry graduate student at Clemson University). Kate also conducted research and was supported by this grant for one month during the summer of 2009 (after her junior year); she will continue these efforts this academic year while applying to chemistry graduate schools. A junior student (Daniel Goldstein) has recently joined the group and is beginning to learn the reactions for this project. He plans to continue working on this research until the end of his senior year. All of the students performing the chemistry supported by this grant benefitted immensely from the experience. Thus, they learned a great deal about a variety of characterizational and spectroscopic techniques, such as Schlenk air-sensitive manipulations and NMR spectroscopy. The PI worked closely with the undergraduate research students on projects supported by this grant throughout the year as much as possible (which was less than is typical due the birth of her son on Dec. 1, 2008, including during the summer months, thus she did not draw any salary from the grant this year).
Thora Maltais reported most of her research results in a poster presentation at the Spring 2009 National American Chemical Society meeting. A significant portion of the cost to travel to Salt Lake City to attend this meeting and present her results came from this grant. Her poster makes up the nugget portion of this report.
