Our first project focuses on the synthesis and reactivity of bimetallic complexes in the activation and sensing of small molecules. A variety of bimetallic and multimetallic centers in nature demonstrate metal-metal cooperativity in binding, recognition, and activation of various substrates. Our roadmap to the cooperativity involves careful design of dinucleating ligand platforms which are tailored for specific substrates and transformations. Specific reactions of interest include reductive coupling and splitting of heteroallenes, reduction of dioxygen, and selective recognition (sensing) of dicarboxylates and sugars.

  Flexible dinucleating ligand allows formation of dinuclear complexes of Ni and Cu. We also demonstrate that the di-Ni complex is capable of binding two molecules of carbon disulfide (right) and positioning them side by side (left). 

 A similar system was synthesized with oxidized Ni (right). This system is capable of binding oxalate between the metal centers (right). The system is selective for oxalate versus other mono- and di-carboxylates. Oxalate coordination is reversed by addition of CaBr2, making it a recyclable oxalate sensor.

A more rigid xanthene-based bis(iminopyridine) ligand forms a di-copper(I) complex. Its reaction with O leads to the isolation of tetranuclear copper(II) cluster with bridging hydroxides, as one of the products (full structure given left). With CO2, a tetranuclear mu-carbonate cluster is isolated (the structure with t-Bu groups is given right).