Research

In the Smith Research Group, we stabilize highly reactive intermediates, isolate metal-ligand multiple bonds, and force Earth-abundant metals to do the work of precious ones.

Our philosophy is grounded in molecular design: by creating specific ligand environments we can stabilize highly reactive metal species that are usually too transient to observe. This allows us to study their reactivity and harness them for difficult chemical transformations.

Metal-Ligand Multiple Bonds

We are pioneers in the chemistry of "atomic ligands", where a single atom (N, C, O, P) is bound to a metal center via a multiple bond.

  • Atomic Ligands: We have developed the chemistry of iron nitrido (Fe≡N) complexes stabilized by tris(carbene)borate ligands. These species are potent atom transfer reagents. More recently, we have extended this work to other atomic ligands, including oxo, sulfido and selenido.
  • Model Complexes: In collaboration with the Goicoechea group, we created the first complex featuring a terminal iron carbide ([Fe]≡C). This serves as a molecular model for intermediates in the industrial Fischer-Tropsch process for CO upgrading.
  • Interstellar Chemistry: Our group uses metal complexes to assemble fleetingly stable small molecules, such as the first structural characterization of the interstellar molecule Phosphorus Nitride (P≡N) in a metal complex.

Spin State Control: Engineering Electronic Ground States

A defining feature of the our research is the use of electron state as a primary design element in catalysis. This tunable variable can be manipulated to unlock new chemical reactivity and physical properties.

"Two State Reactivity"

In many catalytic cycles, the ground electronic state of a catalyst is unreactive toward specific steps in a reaction. We design catalysts that can cross between different spin surfaces during the reaction, allowing them to leverage the properties of multiple electronic states.

  • Design: By carefully designing the ligand field, we create catalysts where the energy barrier to switch spin states is thermally accessible.
  • Application: In alkene isomerization, this spin-crossover acts as a "gate." The high-spin ground state prevents the catalyst from being poisoned by strong bases, while the reactive low-spin state is only accessed when the correct substrate binds.

High Spin Complexes with Metal-Ligand Multiple Bonds

Historically, iron imido (Fe=NR) complexes are active in nitrene group transfer catalysis. By engineering the coordination environment to stabilize a high-spin (S = 2) iron(II) state, we have unlocked new reactivity in which the metal and imido ligand act cooperatively in catalysis.

  • Breakthrough: These high spin complexes exhibit nucleophilic behavior at the imido ligand, allowing them to perform unprecedented transformations like double bond transposition and hydrogen isotope exchange. This fundamentally expands the toolkit of iron imido catalyst reactivity.
  • Extension: Oxygen atom insertion from high spin (S = 2) iron(IV) oxo complexes enables new catalysis for the synthesis of phenols.

Sustainable Electrocatalysis

We are developing molecular solutions to electrocatalysis that is aimed at closing the nitrogen cycle.

  • Nitrate to Ammonia Conversion: Agricultural runoff (nitrate) is a major pollutant. We have designed 3d metal ion macrocyclic complexes that electrochemically reduce nitrate (NO3-) into ammonia (NH3), turning waste into value-added fertilizer.
  • Surface-Conjugated Catalysts: We are bridging the gap between homogeneous and heterogeneous catalysis by attaching well-defined molecular catalysts to graphite electrodes for robust, long-term performance.