William Nunn Lipscomb

(b. 1919)

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(1919–) American inorganic chemist

Born in Cleveland, Ohio, Lipscomb was educated at the University of Kentucky (graduating in 1942) and the California Institute of Technology where he obtained his PhD in 1946. He worked at the University of Minnesota from 1946 to 1959, being appointed professor of chemistry in 1954. In 1959 Lipscomb moved to the chair of chemistry at Harvard where he remained until his retirement in 1990.

Lipscomb is best known for his work on boranes – hydrides of boron first investigated by Alfred Stock in the early part of the century. Boranes have such typical formulae as B2H6, B4H10, B10H14, and B18H22, which immediately appear to the chemist as analogous to the comparable hydrocarbon series, CH4, C2H6, C4H10, etc. However, as boron has only three electrons in its outer shell, it was difficult to see how the covalent electron-pair bonds could work with boron hydrides.

Using low-temperature x-ray diffraction analysis, Lipscomb tackled the problem of investigating the notoriously unstable boranes, producing evidence of some remarkable structures, totally original and completely unsuspected by earlier chemists. The basic concept of a three-center bond was derived from a structure for diborane proposed by H. C. Longuet-Higgins. This differs from the normal covalent bond found in hydrocarbons where adjacent carbon and hydrogen atoms share two electrons. In a three-center bond, a pair of electrons is shared equally by three atoms.

Lipscomb's work on boron hydrides involved new techniques that proved to have a wider application in chemistry and produced results that led to the formulation of more general theories. In particular, Lipscomb produced a theory of chemical effects in nuclear magnetic resonance studies of complex molecules. He also worked on the quantum mechanics of large complex molecules.

His group has also applied low-temperature x-ray diffraction techniques to other substances, including single crystals of such gases as oxygen and nitrogen, other inorganic compounds, and naturally occurring organic compounds. More recently he has turned to determinations of the structures of proteins, enzymes, and other substances of biochemical interest.

Lipscomb received the Nobel Prize for chemistry in 1976.

Subjects: Science and Mathematics.

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