Substrate-Dependent Hydridic and Radical Reactivity of Triiron Hydride Clusters.

The reactivity of iron clusters with one of more μ-hydrides and in the weak field pertains to catalysis on surfaces and biological metal cluster cofactors. As a model, then, a reactivity survey of the weak-field ligated iron hydride clusters FeH () and (FeCO)Fe(μ-H) () (where is a tris(β-diketiminate)cyclophanate) with Brønsted acids, organochlorides, acetyl chloride, boron trihalides, and titanium electrophiles is reported. Complex reacts with Brønsted acids HO and [EtNH][Cl] to afford Fe(OH) () and FeHCl (), respectively, consistent with hydridic reactivity. Clusters and react readily with organochlorides, such as CCl, CHCl, and CHCl, with identified intermediates supporting a radical pathway. Complex reacts with trityl chloride (2 equiv) to selectively afford FeHCl () with reductive elimination of dihydrogen observed. Mixed-valent complex reacts with AcCl to afford (FeCO)FeHCl (). The scope of reactivity displayed implicates possible pathways accessible to larger clusters in biology or on metal surfaces.