Isoelectronic cluster reactivity

These reactions show how the reactivity of a molecule can be altered using the isoelectronic substitution of a CH fragment for a P atom. The higher propensity for cluster formation when a CH fragment in a molecule is replaced by a group 15 atom is important in the syntheses of labile cluster molecules. 

The chemisorption of CO onto 12 different transition metal clusters °° containing more than a few atoms is facile and exhibits little evidence of the dramatic size-sensitive behavior observed for chemisorption of Hj or of N2, even though Nj and CO are isoelectronic. Whether reactions are observed for the atom and the smaller clusters depends on the metal. Similarly the chemisorption reactions of CO with the cluster ions Nb and COn " exhibit little size-selective behavior. Chemisorption is faster onto the cluster ions than onto the respective neutral clusters. Aluminum is the only metal examined thus far for which CO chemisorption is significantly cluster-size sensitive, with Alg being the most reactive cluster. " ... 

Using the above basic ideas it is possible to discuss reactivity patterns and transition state structure in a variety of organic reactions, and to understand the variation of isoelectronic species from transition states to stable hypercoordinated clusters of metallic and nonmetallic elements. 

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