Uiliam Lipskomb American physical chemist, Nobel Prize in Chemistry, 1976 Date of Birth: 09.12.1919 Country: USA

1. Early Life and Education
2. World War II Interlude
3. Career and Contributions
4. Boranes: Unraveling the Enigma
5. Nobel Recognition
6. Later Research and Legacy
7. Personal Life and Honors

Early Life and Education

William Nunn Lipscomb Jr., an American physical chemist, was born on December 9, 1919, in Cleveland, Ohio. His parents, Edna Porter and William N. Lipscomb, moved the family to Lexington, Kentucky, a year after his birth.

After graduating from Henry Clay High School, Lipscomb enrolled at the University of Kentucky, earning his B.S. in Chemistry in 1941. He began graduate studies in physics at the California Institute of Technology that fall. Encouraged by Linus C. Pauling, his professor and later doctoral advisor, he switched to physical chemistry after a year.

World War II Interlude

From 1942 to 1945, Lipscomb halted his academic pursuits to conduct war-related research for the U.S. Office of Scientific Research and Development. In 1945, he resumed his studies at Caltech, receiving his Ph.D. the following year for his dissertation on X-ray crystallography and electron diffraction of organic compounds.

Career and Contributions

After completing his doctorate, Lipscomb joined the University of Minnesota as an Assistant Professor of Physical Chemistry. He became an Associate Professor in 1950 and a full Professor in 1954. In 1959, he moved to Harvard University as Professor of Chemistry, chairing the Chemistry Department from 1962 to 1965. Since 1971, Lipscomb has held the position of Professor of Chemistry Emeritus at Harvard.

Boranes: Unraveling the Enigma

Lipscomb's interest in chemical bonding was piqued at Caltech by the chemistry of boranes, also known as boron hydrides. These rare compounds had been synthesized by earlier generations of scientists, including German chemist Alfred Stock. The molecular structures of boranes were unknown, but their empirical formulas suggested intriguing peculiarities in their chemical bonding. Lipscomb was unconvinced by the interpretation of these peculiarities proposed by Pauling, then a leading authority on chemical bonding theory.

Upon moving to the University of Minnesota in 1946, Lipscomb set out to prove his former teacher wrong. Borane chemistry was not only a mystery but also a formidably difficult field to study because of the volatility, instability, and even explosiveness of the boranes. Lipscomb developed a novel technique for studying them using X-ray diffraction under high vacuum and low temperature. He was able to describe their structures in detail, revealing them to be cage-like polyhedra.

However, Lipscomb sought to solve the riddle of boranes not only empirically but also theoretically. The prevailing theory at the time held that atoms in borane molecules were held together by two-center (covalent) bonds, where two electrons shared between two atoms hold them together. The problem was that this theory could not account for the structure of boranes as Lipscomb established it. Boron atoms simply didn't have enough bonding electrons to share with the number of hydrogen atoms they were known to bind with.

In a collaboration with chemists Bryce Crawford and W. H. Eberhardt in 1953, published the following year in the Journal of Chemical Physics, Lipscomb proposed that the electron deficiency was only apparent. They argued that some of the atoms in borane molecules participated in three-center bonds, where a pair of electrons bonds either three boron atoms or two boron atoms and a hydrogen atom, forming a so-called hydrogen bridge. "We ventured a few prophecies," they later wrote, "consoling ourselves in advance that if we were added to the long list of unsuccessful predictors in borane chemistry, we would be in very good company."

Their concept of three-center bonds proved to be both correct and a key to a new topological theory of chemical bonding in boranes. It explained the structure of boranes and predicted the existence of new compounds. Guided by it, chemists have created a large number of stable cage-like molecules. Moreover, Lipscomb extended this new understanding of chemical bonding to understanding the reactivity of carboranes, which have found applications in the synthesis of polymers with remarkable thermal and chemical resistance. Lipscomb's boranes may also prove useful in anti-cancer radiotherapy. In the journal Science, Russell Grimes speculated that carboranes "will deeply influence the future of organic synthesis" after the "revolution in concepts of the covalent bond" caused by Lipscomb's work on borane chemistry.

Nobel Recognition

In 1976, Lipscomb was awarded the Nobel Prize in Chemistry "for his studies on the structure of boranes illuminating problems of chemical bonding." In his Nobel lecture, Lipscomb remarked, "My original intention in the late 40's was to spend a few years doing some definitive work on boranes and then to set about a systematic description of valence in the vast number of compounds that suffer from an apparent electron deficiency." "I have made but little progress toward this ultimate goal," he added, "but the chemistry of the boranes has grown prodigiously in the meantime, and some of its complexities are now just beginning to be understood systematically." Of his Nobel Prize, he said, "I know now that I have written some good papers on boranes, although I never have been sure before that anybody read them."

Later Research and Legacy

Upon moving to Harvard, Lipscomb shifted his research focus to biochemistry. He focused on elucidating the structures of complex proteins as a means of understanding their mechanisms of function in the human body, since function is determined by protein shape. This work entailed solving enormously complex problems due to the large size of protein molecules. Lipscomb's approach was groundbreaking in its use of X-ray diffraction technology in combination with computational methods. His major triumph in this line of research came with the structural analysis of the digestive enzyme carboxypeptidase A, which led to a proposed mechanism for the enzyme's activity. He is currently working on the regulatory enzyme aspartate transcarbamoylase, which controls steps in the synthesis of essential amino acids in humans and animals. This enzyme is thus crucial to cell growth in all living organisms. While Lipscomb himself considers his work on the digestive enzyme to be his best, his "attack" on aspartate transcarbamoylase may well surpass it if successful.

Lipscomb's achievements are attributed not only to the boldness of his scientific imagination but also to the versatility and flexibility of his approach. As he himself stated, "I am a physical chemist by training. My degree is in physical chemistry. I previously worked in inorganic chemistry... now as a biochemist. But do not look for inconsistencies. It is all structure and function."

Personal Life and Honors

Lipscomb married Mary Adele Davies in 1944. They had a son and a daughter. They separated in 1983, and in the same year, Lipscomb married Jean Evans, a commercial artist. "A country boy on the make," is how science writer Rebecca Rolls has described Lipscomb. He runs his laboratory with a de facto command post and wields a wicked sense of humor. His colleagues and students are deeply attached to him and, in keeping with his Kentucky upbringing, address him as "Colonel." Lipscomb plays the clarinet with near-professional skill ("Chamber music is the passion of my life," he has said), quotes Lewis Carroll in his scientific papers, and is a member of the Sherlock Holmes group known as Baker Street Irregulars.

Lipscomb has received numerous awards and honors, including the American Chemical Society Award for Distinguished Service in the Advancement of Inorganic Chemistry (1968), the George Ledlie Prize of Harvard University (1971), the Peter Debye Award in Physical Chemistry (1973), and the American Chemical Society's Ramsay Award (1976). He is a member of the American Academy of Arts and Sciences, the U.S. National Academy of Sciences, and a foreign member of the Royal Netherlands Academy of Arts and Sciences. He has received honorary degrees from the University of Kentucky, Harvard University, the University of Munich, Long Island University, Rutgers University, and Marietta College.