Controlled Expansion of a Strong‐Field Iron Nitride Cluster: Multi‐Site Ligand Substitution as a Strategy for Activating Interstitial Nitride Nucleophilicity

Multimetallic clusters have long been investigated as molecular surrogates for reactive sites on metal surfaces. In the case of the μ4‐nitrido cluster [Fe4(μ4‐N)(CO)12]−, this analogy is limited owing to the electron‐withdrawing effect of carbonyl ligands on the iron nitride core. Described here is the synthesis and reactivity of [Fe4(μ4‐N)(CO)8(CNArMes2)4]−, an electron‐rich analogue of [Fe4(μ4‐N)(CO)12]−, where the interstitial nitride displays significant nucleophilicity. This characteristic enables rational expansion with main‐group and transition‐metal centers to yield unsaturated sites. The resulting clusters display surface‐like reactivity through coordination‐sphere‐dependent atom rearrangement and metal–metal cooperativity. Wachstumsplan: Der Austausch mehrerer CO‐Liganden im Starkfeldcluster [Fe4(μ4‐N)(CO)12]− durch stärkere Donoren verwandelt ein unreaktives interstitielles Nitrid in ein gutes Nucleophil. Diese Eigenschaft ermöglicht den systematischen Einbau reaktiver Zentren in das Clustergerüst auf eine Art und Weise, die an die Einführung von Fehlstellen in heterogene Oberflächen erinnert.