Trovitch Laboratory
 Physical Science Building, D-318
School of Molecular Sciences
 Arizona State University
Tempe, AZ, 85287
 Call: (+1) 480-965-7728
Email: ryan.trovitch@asu.edu

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About RJT




  TROVITCH RESEARCH GROUP

INORGANIC AND ORGANOMETALLIC CHEMISTRY



Overview


    For each project area outlined below, we are seeking to develop sustainable homogenous or site-isolated catalysts that operate efficiently under mild conditions. In pursuing these projects, our interests align with ASU's Design Aspirations to conduct use-inspired research, leverage our place and transform society. While we continue to study catalysts that are supported by traditional ligand scaffolds, the application of non-innocent ligands represents a cross-cutting theme that ties together much of our ongoing work. Such ligands are promising for first-row metal catalyst development as they are capable of transferring electrons to and from the metal throughout the course of a transformation, allowing it to retain its preferred oxidation state. Specifically, our laboratory is interested in designing and utilizing chelates that can coordinate to a transition metal beyond their historically investigated redox-active cores. We believe that this approach might allow for the development of catalysts that exhibit improved stability and activity over their previously investigated counterparts. In addition, it is hoped that the flexibility and modularity of our chelates will offer an opportunity to develop bifunctional catalysts (which operate through chemical ligand involvement) and allow for the isolation of entirely new precatalyst structures, which may in turn mediate novel catalytic transformations.





Current Projects


1) Development of Biologically Benign Transition Metal Catalysts

    The principal objective of this project is to design and study the catalytic reaction chemistry of complexes containing non-toxic transition metals. Our approach differs from current efforts in base metal catalysis in that we rely on non-innocent ligands that are capable of supporting a metal center beyond their redox-active cores. Recently, we discovered that the reduction of (Ph2PPrPDI)MnCl2 allows for the preparation of (Ph2PPrPDI)Mn, shown below (J. Am. Chem. Soc. 2014, 136, 882-885). Although the formal oxidation state of the metal is Mn(0), an electronic structure analysis of this complex revealed that two of the metal-localized electrons have been fully transferred to the redox-active PDI chelate. The unpaired electron that remains in a Mn-based orbital renders (Ph2PPrPDI)Mn an extremely efficient catalyst for the hydrosilylation of carbonyl containing substrates. At catalyst loadings of only 0.01 mol%, the hydrosilylation of either 2-hexanone or cyclohexanone with an equimolar quantity of phenylsilane was complete within 5 min at 25 C (TOF > 75,000 h-1, highly exothermic).

                   

Expanding upon this methodology, we are currently seeking to prepare Mn, Fe, Co, and Ni catalysts that can be utilized for a broad range of organic transformations (e.g., hydrogenation, C-C bond cross-coupling, or olefin metathesis). Furthermore, we have expanded our scope of base metal catalyst development to include supporting ligands that are not pyridine- or phosphine-derived. If complexes supported by common food and drug additives can be used to effectively catalyze organic transformations, they can simply be left in pharmaceutical products during the final stages of synthesis, when precious metals are avoided because of their inherent toxicity.


2) Utilization of CO2 as a Chemical Feedstock

    Our work in this area seeks to expand the scope of carbon dioxide utilization in large scale chemical synthesis by unveiling a molecular level understanding of the catalytic capture and incorporation of carbon dioxide from either flue gas or the atmosphere into value-added organic products. The benefits of accomplishing this challenge remain two-fold; advances in this area could lower overall carbon dioxide emissions and circumvent the current industrial demand for oxidative petroleum consumption. We are currently focused on preparing redox-active ligand supported rare earth and early transition metal complexes that can bind and reducecarbon dioxide using chemical reductants. Methods of incorporating metal-bound carbon dioxide into unsaturated or otherwise functionalizable organic substrates are also currently being investigated.




3) Designing Catalysts for Solar Fuels Production

    As the widespread utilization of an artificial photosynthetic cell will likely require that the system be built from inexpensive and readily available materials, we are currently exploring the development of earth-abundant transition metal catalysts for water splitting, proton reduction, and carbon dioxide reduction in collaboration with ASU’s Center for Bio-Inspired Solar Fuel Production. Eyeing nature’s design of the oxygen evolving complex in Photosystem II as a starting point, we are seeking to design simplified homogeneous and supported Mn catalysts that efficiently mediate water oxidation. Simultaneously, our laboratory is engaged in the development of Fe, Co, and Ni proton and carbon dioxide reduction catalysts that have the capacity to operate in a bifunctional fashion. Catalysts that exhibit exceptional activity and stability will ultimately be incorporated into a dye-sensitized electrochemical cell that is capable of producing either hydrogen or carbon-based fuels directly from sunlight.



4) The Electrocatalytic Reduction of CO2 to Formaldehyde

    In collaboration with Mu-Hyun Baik’s group at KAIST, we are currently working to develop a multicomponent catalyst that is capable of mediating the electrocatalytic reduction of carbon dioxide to CO along with simultaneous hydride transfer to produce formaldehyde or formaldehyde-related reduction products. Ideally, such a transformation would mimic the Fischer-Tropsch process but not require significant heat or pressure inputs. While the targeted catalysts draw inspiration from previously reported carbon dioxide to CO reduction pathways, our approach aims to take advantage of closely tethered hydride and Lewis acidic sites. It is hoped that sufficiently hydridic metal complexes will transfer H- to the carbon atom of a neighboring CO ligand that is activated by a charge-polarizing cation. A catalyst of this type would be capable of utilizing protons and electrons to convert carbon dioxide into formaldehyde and possibly methanol, rendering it a valuable component for solar-to-fuel constructs

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5) Modification of Downstream Biomass Derivatives through C-O Bond Cleavage
   
    With an ever increasing global demand for crude oil, it is essential that renewable alternatives to petrochemical feedstocks are developed. We are addressing this challenge by designing late transition metal complexes that are capable of mediating the selective, catalytic deoxygenation of bio-based organics. Although recent reports have described the degradation of non-food source biomass into a myriad of organic products, less attention has been paid to the transformation of these “platform molecules” into chemicals that are currently synthesized from petroleum. Our efforts in this area ware initially focused on the preparation of Rh complexes that could reductively cleave C-O and C-N bonds under mild conditions; however, these investigations have led us to pursue the development of electron rich Fe, Co and Ni complexes. We desire to control the degree of substrate reduction in a stepwise fashion; however, the production of second generation, non-ethanol biofuels remains a secondary target.




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