Graham, William A.G. Professor Emeritus M.A., University of Saskatchewan Ph.D., Harvard University Phone: (780) 492-3255 E-mail: bill.graham@ualberta.ca

In the early 1980's, certain metal complexes were found to undergo an unprecedented reaction at room temperature with the carbon-hydrogen bonds of saturated hydrocarbons:

Ligands are represented by L and C-H bond by RH. The product is much more reactive than the initial hydrocarbon and so the C-H bond is said to have been activated. There is a widespread belief that C-H activation by transition metal complexes will provide new and more efficient processes for the petrochemical industry.

Our first work in C-H activation utilized photochemical reactions of (-C₅Me₅)Ir(CO)₂. More recently we discovered that a new family of complexes, the pyrazolylborates, are much more efficient photochemical activators and will activate benzene thermally (i.e., in the dark) at 100°C. The structures of a ligand of this type and some of its complexes are shown on this page. The substituents on the pyrazole part of the ligand can of course be changed to fine-tune the properties of the complex.

Ongoing research in my group involves (a) the design of new metal complexes capable of photochemical or thermal C-H activation; (b) investigation of the rates and mechanisms of these processes; (c) a search for reactions of the primary C-H activation products leading to useful products, including design of catalytic cycles.

Publications:

W.A.G. Graham, "From Silicon-Hydrogen to Carbon-Hydrogen Activation", J. Organomet. Chem. 1986, 300, 81.

C.K. Ghosh and W.A.G. Graham, "Efficient and Selective Carbon-Hydrogen Activation by a Tris(pyrazolyl)borate Rhodium Complex", J. Am. Chem. Soc. 1987, 109, 4726.

C.K. Ghosh and W.A.G. Graham, "A Rhodium Complex That Combines Benzene Activation With Ethylene Insertion. Subsequent Carbonylation and Ketone Formation", J. Am. Chem. Soc. 1989, 111, 375.

C.K. Ghosh, J.K. Hoyano, R. Krentz and W.A.G. Graham, "A Hydridovinyliridium Complex More Stable Than Its ²-Ethylene Isomer", J. Am. Chem. Soc. 1989, 111, 5480.

W.A. Kiel, R.G. Ball and W.A.G. Graham, "Carbonyl--hexamethylbenzene Complexes of Osmium. Carbon-Hydrogen Activation by (-C₆Me₆)Os(CO)(H)₂", J. Organomet. Chem. 1990, 383, 481.