As Kenneth B. Wiberg, professor emeritus of chemistry celebrates his 60th year at Yale, he reflects on his achievements, most memorable moments, and the changes he has seen.
Wiberg joined Yale Chemistry in 1962 as a professor, teaching organic chemistry and conducting research in his laboratories. He also served as department chair from 1968 – 1971.
His many contributions to chemistry and to the department are marked by his passion for research, dedication to teaching, and enthusiasm to “stay ahead of the curve.” As a result, he had a pronounced influence on the department’s positive reputation and development.
When Wiberg came to Yale in 1962 at the invitation of then Chair Harry Wasserman, the Department of Chemistry became the world’s leading center for physical-organic chemistry. Early in his career, Wiberg did landmark work on the formation and rearrangement of carbon cations. He is known for the wide range of physical and computational techniques that he skillfully brought to bear on determining the properties of carbon-carbon bonds, especially when strained by inclusion in small-ring polycyclic compounds.
Not only did he succeed in preparing compounds that many organic chemists thought incapable of existence, but he also examined their spectroscopic and thermodynamic properties, and used these results to test and improve burgeoning computational methods.
His early study of small rings was on cyclopropane, a three-membered ring of carbon that was thermally converted into propene. He collaborated with physical chemists to study this conversion. Procedures were developed to prepare both cis and trans 1,2-dideuterium labeled derivatives. The thermolysis led to both cis-trans conversion and propene formation showing that the initial process was cleavage of C-C bond to form a diradical.
Later, having made bicyclobutane, Wiberg attempted what others thought impossible, to add another three-membered ring to give propellane. To examine the possible stability of this compound, he needed a computer to carry out ab initio calculations for propellane and several possible mechanisms for its dissociation. Wiberg secured the department’s first computer and went on to prove the requisite stability. This led to its synthesis. Several years later, chemist Paul Baran made use of its strain energy in making natural products. What started as chemical curiosity for Wiberg resulted in hundreds of papers incorporating his work, not to mention the introduction of computational chemistry to the department.
Wiberg humbly summarizes, “my lab made strange compounds and [performed] calculations of their properties.” But more than that, he and other professors trained the next generation of leaders in physical-organic chemistry while simultaneously bridging subdisciplines and promoting collaboration across the department – a hallmark that still exists to this day.
“There are two kinds of departments. Some are very divisionally head-up; the organic chemists talk with the organic chemists; the inorganic chemists talk with the inorganic chemists. Yale was very different,” he said. “I did collaborative work with several of my colleagues. And it was a very pleasant place to work. I enjoyed going to work there.”
The physical-organic chemistry group at the time, consisting of Wiberg, Harry Wasserman, Jerome Berson, Martin Saunders, and Michael McBride, were an all-star team working on the synthesis and reactions of compounds. Wiberg was responsible for bringing Berson into this group as well as the formation of other groups.
When he noticed the need for chemical physicists, he pushed for them, and successfully hired Steven Colson and Al Smith. To promote the emerging field of chemical biology, he and others brought in Alanna Schepartz, the first woman faculty member in the chemistry department. He also helped hire the current chair of the department, Professor Kurt W. Zilm.
Another turning point that set the department on a different track, Wiberg explains, was the building of the Kline Chemistry Laboratory. This dedicated research building solved the space constraints for an ever-growing department that had been confined to the Sterling Chemistry Laboratory.
Reflecting on a moment that stood out to him, Wiberg recalls a time when he was just ready to move to Seattle to join the University of Washington, a very famous chemist told me not to make myself too vocal, to keep my head down. When the organic chemists wanted to purchase their first analytical instrument, an infrared spectrometer, Wiberg spoke up and convinced the group to buy a newer, better one. He said, “it was an interesting moment in my career. It paid to make my thoughts known.”
Other colleagues who were influential to his career were his Ph.D. supervisor Professor William Doering and Professor Harry Wasserman, who he talked with several times a week about research ideas.
“In research, there are two choices we can make,” he said. “Some people choose to experiment in one area, or some people choose to do lots of different things. I chose to do lots of different things. The variety was fun.”
Ever the dedicated professor, Wiberg once fell and broke his wrist while teaching the big sophomore organic-chemistry class and continued to teach instead of seeking medical attention. A graduate student who was trained in first aid wrapped his arm in a sling, and he used his non-dominant hand to draw diagrams on the blackboard. He recalls, “the students thought it was hilarious.”
His advice to the professor in their first year? “Work hard,” he said. “I realized to move along you’ve got to get things done. Try anything. It might work. I had been lucky because I published over 400 papers” – 478 to be exact.
Wiberg’s love of chemistry started at a young age, when he and an elementary school friend performed experiments from a chemistry set. He went on to complete a three-year chemistry program at Brooklyn Technical High School before earning a bachelor’s degree at the Massachusetts Institute of Technology in 1948. He earned his Ph.D. in organic chemistry in 1950 from Columbia University, where he studied reaction mechanisms using stereochemistry alongside Professor William Doering.
Wiberg is a member of the National Academy of Sciences, and the American Association of Arts and Sciences, and a fellow of the American Academy of Arts and Sciences. He has won the Arthur C. Cope Award for his achievements in the field of organic-chemistry research, the American Chemical Society Award in Physical-Organic Chemistry, and the Pauling Award.
In retirement, Wiberg has written his memoir and has published several papers on computational studies that he recently completed. He has done a good deal of traveling and continues to lecture on chemistry to his community of friends.