Energetics and Structures of Gas Phase Ions: Macromolecules, Clusters and Ligated Transition Metals

Abstract

In this paper a number of methods for determining thermochemical data for gas phase ions are described. Of most importance are ion equilibrium measurements where emphasis is placed on the differences in our work from earlier studies. Most of the paper is devoted to novel applications. These emphasize transition metal centers, the roles ligands play in activating them, and the very subtle interplay between the nearly degenerate s and d orbitals. A case study of sequential ligation by dihydrogen of the entire first transition metal series is given. Generally the first solvation sphere closes at n = 6 but interesting exceptions are noted. High level ab initio calculations are done on each system allowing structural information and details of the bonding to be obtained. Other systems discussed include a few second row metals, the role of the Cp ligand in activating Co+ and the discussion of a novel cluster assisted σ-bond activation scheme. The paper concludes with a demonstration that the structurally important ion chromatography technique can be used to extract thermochemical information on macromolecules under favorable conditions.