Rory Waterman

Inorganic Chemistry

Assistant Professor

Rory.Waterman@uvm.edu
phone: 802-656-0278
office: Cook Rm A129

Research in the Waterman group applies the synthesis of novel inorganic and organometallic systems to define new reactivity and catalysis. Students will have the opportunity to prepare and fully characterize new complexes through a variety of spectroscopic techniques (e.g., NMR, IR, UV-vis, EPR), X-ray crystallography, and analytical methods. These complexes are frequently air-sensitive, and students learn to manipulate the complexes using high-vacuum and Schlenk techniques or in a glovebox. These complexes will target the catalysis of chemically important processes such as bond-forming and selective oxidation reactions.

A key reaction in element-element bond formation is dehydrocoupling, where two molecules with element-hydrogen bonds formally exchange E-H bonds to form E-E and H-H bonds. Dehydrocoupling is a very clean and efficient reaction taking often commercially available starting materials and providing element-element bonds with hydrogen (H₂) as the only byproduct. However, for many elements this reaction is not facile, and a catalyst is needed. We have found that zirconium complexes supported by triamidoamine ligands such as (N₃N = N(CH₂CH₂NSiMe₃)₃^3-) are effective for dehydrocoupling a range of primary and secondary phosphines. Through careful mechanistic study, we have determined that this catalysis proceeds via σ-bond metathesis steps as shown to the right.

Using this knowledge we are applying this system to catalyze other element-element bond formation reactions. Using the predictive power of our sigma-bond metathesis-based mechanism, we have recently demonstrated selective P-Si and P-Ge bond formation using our zirconium catalysts, and in a simple periodic analogy, we have shown, for the first time, that catalytic dehydrocoupling of arsines is possible. Our continued efforts in this area are directed at addressing questions in molecular synthesis, materials science, and energy.

A second project involves synthesis of new phosphorus-based ligand architectures to explore catalytic reactions. One reaction we are interested in is alpha-elimination, where a low-valent main group fragment (:ER_m) is extruded from an early transition-metal (L_nM) center such as zirconium or niobium, as depicted in the proposed catalytic cycle shown in the figure to the right. This reaction has seen limited attention in the literature, and we seek to exploit it for bond-forming catalysis.

Selected Publications

Roering, A. J.; Davidson, J. J.; MacMillan, S. N.; Tanski, J. M.; Waterman, R. "Mechanistic Variety in Zirconium-Catalyzed Bond-Forming Reaction of Arsines" Dalton Trans., 2008, DOI: 10.1039/b718050k.

Waterman, R. "Dehydrogenative Bond-Forming Catalysis Involving Phosphines" Curr. Org. Chem. 2008, in press (invited review for a thematic issue: Organometallic Chemistry, Coordination Chemistry, and Catalysis).

MacMillan, S. N.; Tanski, J. M.; Waterman, R. "Insertion of Benzylisocyanide into a Zr-P bond and Rearrangement. Atom-Economical Synthesis of a Phosphaalkene" Chem. Commun. 2007, 4172-4.

Roering, A. J.; MacMillan, S. N.; Tanski, J. M.; Waterman, R. Zirconium-Catalyzed Heterodehydrocoupling of Primary Phosphines with Silanes and Germanes. Inorg. Chem. 2007, 46, 6855-7.

Waterman, R. "Selective Dehydrocoupling of Phosphines by Triamidoamine Zirconium Catalysts" Organometallics 2007, 26, 2492-4.