Evidence of three-electron covalent bond firms

Abstract

Three groups of chemists from Columbia University and Rutgers University have developed evidence for a little-explored form of covalent bonding that may have wide implications in organic chemical reactivity [ J. Am. Chem. Soc. , 109, 7204 (1987)]. The bond in question consists of three shared electrons. The bond turned up initially in studies of chlorine atoms bonded to pyridine nuclei. But the chemists who uncovered this bond type have since found it in other systems. They conclude that it may govern interactions of a wide variety of free radicals with electron-pair donors. The discovery of the unusual pyridine-chlorine bond began with efforts by organic chemistry professor Ronald C. Breslow and postdoctoral fellows Michael Brandl and Jurgen Hunger at Columbia to uncover the reason for highly selective chlorination of steroids esterified with nicotinic or isonicotinic acids [ J. Am. Chem. Soc. , 109, 3799 (1987)]. This work, supported by the National Science Foundation, may be useful for commercial, nonf...