Two-reagent reactions of iron clusters with ammonia and deuterium: Saturated compositions and the kinetics of reactions of deuterium with ammoniated clusters

Studies of two-reagent reactions of iron clusters with ammonia and deuterium are described. The compositions of clusters saturated with both ammonia and deuterium have been determined, and indicate that the ammonia binds nondissociatively to iron clusters and to different sites than the deuterium. Rate constants for the reaction of the first deuterium molecule with ammoniated clusters have been measured. In general, low ammonia coverage (one to three molecules) has either little effect on cluster reactivity, or in the case of unreactive bare clusters, increases reactivity dramatically. Clusters saturated with ammonia show general reactivity decreases, although again the least reactive bare clusters show dramatic increases in reactivity when covered with ammonia molecules. Interesting cluster activation and deactivation effects are seen. Possible mechanisms for these reactions are discussed.