Using first-principles calculations with predictive capability we show that organic molecules having negative electron affinity can be transformed to superhalogens with electron affinities far exceeding that of chlorine, once its core and ligand atoms are suitably replaced. The discovery of organic superhalogens could have significant impact in chemistry, allowing the synthesis of new materials and compounds.

It has been noticed that Figure 7 in this Full Paper was reproduced incorrectly. The correct Figure is depicted below. Figure 7. Geometries of next higher-energy isomers of neutral C 13-m H 9-m N m (m = 0-3, 9) molecules. Bond lengths are given in Š.

Stabilization of multiply charged ions in the gas phase has been one of the most fundamental challenges in chemistry since it is hindered either because of fragmentation or auto-electron detachment. Closo-borane B 12 H 12 2À is among the best known multiply charged di-anion in chemistry where the second electron is bound by 0.9 eV. We show that transition metal based organo-metallic di-anions such as Cr[BC 5 (CN) 6 ] 2 can be even more stable than B 12 H 12 2À where the second electron is bound by 2.58 eV. This is in contrast to C 6 H 6 which is unstable even as a mono-anion. The unusual stability of the organo-metallic complex is brought about by having the added electrons simultaneously satisfy three separate electroncounting rules, namely the octet rule, the aromaticity rule, and the 18-electron rule. Mono-anionic Mn[BC 5 (CN) 6 ] 2 which is isoelectronic with di-anionic Cr[BC 5 (CN) 6 ] 2 is also found to be very stable. The design of unusually stable singly and multiply charged organo-metallic negative ion complexes in the gas phase opens the door to the synthesis of new salts with potential applications as organic cathodes and electrolytes in Li ion-batteries and beyond. Equally important, electron counting rules can be used effectively to guide the synthesis of electronegative species beyond super-and hyperhalogens, and hence opening the door for new oxidizing agents.Over the past 30 years the study of multiply charged molecular ions has been a topic of great interest 1 not only because they enable a fundamental understanding of interstellar chemistry but also for their potential as building blocks of salts and Zintl phase compounds, fusion devices, high intensity ion sources, and use in analytic mass spectrometry of large biomolecules. Multiply charged species are commonly seen in solutions or in a condensed phase where they are stabilized either by counterions or interaction with the solvent molecules. Their stability in the gas phase, however, is governed by a delicate balance between the repulsive Coulomb forces and attractive interaction generated by chemical bonding and charge/induceddipole interactions. Small multiply charged molecular negative ions in the gas phase are seldom stable due to spontaneous emission of electron (the so-called auto-detachment) or fragmentation into mono-anions. In the early 1990's observation of long-lived cluster di-anions such as C 60 2À could be explained 2 by the existence of substantial Coulomb barriers that hinder the emission of one of the excess electrons. More recently, electronic stability of di-anionic metal hexauoride complexes such as ZrF 6 2À , rst predicted by theory, 3-5 has been conrmed by photoelectron spectroscopy experiments, 6 but their thermodynamic stability is not addressed. How small a cluster can bind two extra electrons without auto-detaching or fragmenting remains an unanswered question. A classic example of a thermodynamically stable di-anion is B 12 H 12 2À. This cluster belongs to the class of closo-boranes, B n H n 2À , whose stability g...

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