GAS-PHASE ION CHROMATOGRAPHY - TRANSITION-METAL STATE SELECTION AND CARBON CLUSTER FORMATION

Gas-phase ion chromatography can separate ions that have the same mass but differ in isomeric structure or electronic configuration. The mai n 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 inclu de state-selective reactivity, excited state deactivation, and state-s elective ligand binding energies. For clusters, ion chromatography was used to determine the structure of pure carbon cluster ions as a func tion of size from C4 to C84. The results indicate that carbon grows fi rst in linear chains, transforms to monocyclic planar rings at about C -10, and forms new families of planar bi-, tri-, and tetracyclic rings at C20, C30, and C40, respectively. Fullerenes, which mysteriously ap pear at C30 and dominate by C50, are generated by heating the planar r ing systems above an isomerization barrier rather than by growth of gr aphite precursors.