Lipscomb, William Nunn (1919-)

US chemist who studied the relationships between the geometric and electronic structures of molecules and their chemical and physical behaviour. Lipscomb was born in Cleveland, Ohio, and studied at the University of Kentucky and the California Institute of Technology. He became professor at Harvard 1959. Lipscomb studied the boron hydrides and their derivatives and put forward bonding theories to explain the structures of electron-deficient compounds in general. He developed low-temperature X-ray diffraction methods to study simple crystals of nitrogen, oxygen, fluorine, and other substances that are solid only below liquid nitrogen temperatures. Lipscomb went on to investigate the carboranes and the sites of electrophilic attack on these compounds, using nuclear magnetic resonance spectroscopy (NMR). This work led to the theory of chemical shifts. The calculations provided the first accurate values for the constants that describe the behaviour of several types of molecules in magnetic or electric fields. They also gave a theoretical basis for applying quantum mechanics to complex molecules.