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Chem 3000 February 26 th , 2009 Literature Presentation “Towards Uranium Catalysts”

Chem 3000 February 26 th , 2009 Literature Presentation “Towards Uranium Catalysts” Fox, A.R; Bart, S.C; Meyer, K; Cummins, C.C. Uranium as a Catalyst. Bind uranium to a ligand framework. Exploit catalytic activity of uranium. Complex uranium to small inert molecules.

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Chem 3000 February 26 th , 2009 Literature Presentation “Towards Uranium Catalysts”

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  1. Chem 3000 February 26th, 2009 Literature Presentation “Towards Uranium Catalysts” Fox, A.R; Bart, S.C; Meyer, K; Cummins, C.C.

  2. Uranium as a Catalyst • Bind uranium to a ligand framework • Exploit catalytic activity of uranium • Complex uranium to small inert molecules Fox, A.R; Bart, S.C; Meyer, K; Cummins, C.C. Towards Uranium Catalysts. Nature2008, 455, 341-349

  3. Objectives Previously Studied New Goals • Hydrogenation of alkenes • Oligomerization • Dimerization • Hydrosilation • Hydroamination of terminal alkynes • Carbon-hydrogen bond activation • Dinitrogen binding and reduction • Carbon monoxide binding • Carbon dioxide reduction • Azide and amine activation • Reactions of unsaturated groups and polymerizations Fox, A.R; Bart, S.C; Meyer, K; Cummins, C.C. Towards Uranium Catalysts. Nature2008, 455, 341-349

  4. Background - Uranium • Provides a source of carbon-free energy (nuclear power) • Used in nuclear warfare • Is the heaviest naturally occurring element of the periodic table Fox, A.R; Bart, S.C; Meyer, K; Cummins, C.C. Towards Uranium Catalysts. Nature2008, 455, 341-349

  5. Why Uranium? • Readily available • Radioactivity • Stable oxidation states • f orbitals m = +1, -1 m = +2, -2 m = +3, -3 http://www.uky.edu/~holler/html/chemistry.html

  6. Haber – Bosch Process N2(g) + 3H2(g) 2NH3 (aq) Haber, F. Ammonia. German Patent DE 229126 (1909) Odom, A.L; Arnold, P.L; Cummins, C.C. Heterodinuclear Uranium/Molybdenum Dinitrogen Complexes. J. Am. Chem. Soc.1998, 120, 5836-5837 Cloke, F.G.N; Hitchcock, P.B. Reversible Binding of Dinitrogen by a Uranium (III) Pentalene Complex. J. Am. Chem. Soc.2002, 124, 9352-9353 Fox, A.R; Bart, S.C; Meyer, K; Cummins, C.C. Towards Uranium Catalysts. Nature2008, 455, 341-349

  7. Uranium and Dinitrogen Binding and Reduction N U N U N N σ* π* Bond Order = 3 Bond Order = 2.5 π σ

  8. Relevance • Nitrogen and Uranium abundance • Ammonia and fertilizers • Novel chemistry Fox, A.R; Bart, S.C; Meyer, K; Cummins, C.C. Towards Uranium Catalysts. Nature2008, 455, 341-349

  9. End-on Binding of Dinitrogen Evans, W. J, Kozimor, S. A, Ziller, J.W. A monometallic f element complex of dinitrogen: (C5Me5)3U(ƞ1-N2). J. Am. Chem. Soc.2003, 125, 14264 - 14265

  10. Results – End-on Coordination Evans, W. J, Kozimor, S. A, Ziller, J.W. A monometallic f element complex of dinitrogen: (C5Me5)3U(ƞ1-N2). J. Am. Chem. Soc.2003, 125, 14264 - 14265

  11. Synthesis of Ligand for Binding and Reduction of N2 R = SiiPr3 • Intermediate of UCp*I2 (not shown) Cloke, F.G.N; Hitchcock, P.B. Reversible Binding of Dinitrogen by a Uranium (III) Pentalene Complex. J. Am. Chem. Soc.2002, 124, 9352-9353

  12. Side-on Binding of Dinitrogen R = SiiPr3 Cloke, F.G.N; Hitchcock, P.B. Reversible Binding of Dinitrogen by a Uranium (III) Pentalene Complex. J. Am. Chem. Soc.2002, 124, 9352-9353

  13. Results – Side-on Coordination • % Yield = 40% Cloke, F.G.N; Hitchcock, P.B. Reversible Binding of Dinitrogen by a Uranium (III) Pentalene Complex. J. Am. Chem. Soc.2002, 124, 9352-9353

  14. Conclusions • Uranium and ligands • End-on Vs. Side-on • Activation and reduction • Ammonia

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