Gas-Phase Ion Chromatography: Transition Metal State Selection and Carbon Cluster Formation

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Science  04 Jun 1993:
Vol. 260, Issue 5113, pp. 1446-1451
DOI: 10.1126/science.260.5113.1446


Gas-phase ion chromatography can separate ions that have the same mass but differ in isomeric structure or electronic configuration. The main features of this technique are briefly outlined, and applications to a series of problems in transition metal chemistry and carbon cluster chemistry are described. Examples in transition metal chemistry include state-selective reactivity, excited state deactivation, and state-selective ligand binding energies. For clusters, ion chromatography was used to determine the structure of pure carbon cluster ions as a function of size from C4 to C84. The results indicate that carbon grows first in linear chains, transforms to monocyclic planar rings at about C10, and forms new families of planar bi-, tri-, and tetracyclic rings at C20, C30, and C40, respectively. Fullerenes, which mysteriously appear at C30 and dominate by C50, are generated by heating the planar ring systems above an isomerization barrier rather than by growth of graphite precursors.