Metal clusters housed within the active sites of metalloproteins catalyze challenging and important multielectron redox reactions, such as water oxidation and dinitrogen fixation. In contrast to the transition metal employed in many synthetic systems, biological clusters are constituted by earth-abundant usually late first row transition metals, and each metal center in the cluster reacts in a cooperative fashion to effect the desired chemical transformation. In principle, strategically-designed multinuclear metal complexes could access similar reactivity; however, few synthetic systems have been reported. In an attempt to control the parameters that influence cooperativity and cluster reactivity (e.g., metal-metal distance, electronic environment of each metal), we have developed macrobicycles as ligands for trinuclear complexes. These organic scaffolds enforce unusual steric and electronic constraints on the metal centers, affording reactive complexes which activate a wide range of small molecule substrates, including nitrous oxide, azide, dioxygen, and dinitrogen. The details of these reactions and the proposed mechanisms will be discussed.

Small molecule activation by trinuclear cyclophane complexes

248th National Meeting (2014)

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