Research in our group is broadly aimed at developing fundamental aspects of inorganic chemistry toward addressing problems of societal significance at large. Focusing primarily on synthetic and mechanistic inorganic and organometallic chemistry and guided by quantum chemical methods, our studies strive to systematically advance catalytic methods of synthesis as a technological solution to the challenge of sustainable development. In particular, we are working to master small molecule transformation via proton- and electron-transfer in pursuing effective functional modeling of various biosynthetic redox processes, introduce novel synthetic paradigms in organofluorine chemistry, and integrate our fundamental investigations into new and/or efficient practical synthetic methods. Specific research directions are outlined in the following.

Redox Catalysis: Efficient Synthesis with Protons and Electrons
Synthetic processes in which reactants undergo changes in their formal oxidation states are broadly represented in nature and chemical industry. The manner in which reductant surrenders its electrons and oxidant gains them differs between the two realms principally, although not universally, in that biological systems manage conversions of complementary substrates at dedicated enzymatic sites via external charge transport, while industrial processes rely on a single type of catalyst to activate and rearrange bonds between reactants. Many of the current industrial synthetic processes can benefit from fast kinetics and good selectivity associated with biochemical redox pathways under mild conditions and low driving forces. To explore the potential of biomimetic approaches to improve energy- and substrate efficiency of applied redox syntheses, we are studying well-defined transition metal redox catalysts for reductions and oxidations of small molecule substrates via proton- and electron transfer. We work to couple these catalyzed redox transformations together via external transport of protons and electrons within the electrochemical framework of a fuel or electrolytic cell and carry out net chemical redox reactions in such bio-inspired manner. Our broader objectives are to develop a better understanding of the function of the corresponding redox enzymes, uncover rational principles for optimization of redox catalysis, and advance efficient methods to interconvert chemical and electrical energy.

Catalytic Construction of C-F Bonds: Mild and Efficient Metal-Mediated Synthetic Methodologies
A large variety of biologically-active compounds and materials derive their unique physical and chemical properties from the presence of C-F bonds. The overwhelming majority of existing methods of C-F bond synthesis rely on secondary stoichiometric fluorinating reagents, few of which are broadly applicable, reactive and selective, while the more effective reagents, as a rule, pose elaborate hazards in their production, handling and use in the actual synthetic procedures. Catalytic fluorination methods, in which a recyclable transition-metal catalyst is used in a synthetic procedure in combination with a readily available, easily handled inorganic source of fluoride to yield a value-added product with new C-F bonds, would improve synthetic accessibility of organofluorine compounds and promote advances in other fields reliant on these products. Development of such methods is the broad goal of this project, which we pursue through studies of novel elementary transformations of organometallic complexes that result in formation of C-F bonds. Properly optimized, these essential reaction steps are envisioned to form the basis of efficient and readily applicable catalytic fluorination methods that rely on primary sources of F¯, recyclable catalysts and straightforward synthetic protocols, while rivaling the high reactivity and selectivity of elaborate fluorinating reagents. Our studies, by definition, do not involve the use of highly hazardous fluorinating reagents.

1) "Synthesis of Tungsten Complexes that Contain Hexaisopropylterphenyl-substituted Triamidoamine Ligands, and Reactions Relevant to the Reduction of Dinitrogen to Ammonia," D. V. Yandulov and R. R. Schrock; Can. J. Chem., 83, 341-357 (2005).

2) "Studies Relevant to Catalytic Reduction of Dinitrogen to Ammonia by Molybdenum Triamidoamine Complexes," D. V. Yandulov and R. R. Schrock; Inorg. Chem., 44, 1103-1117 (2005).

3) "Catalytic Reduction of Dinitrogen to Ammonia at a Single Molybdenum Center," D. V. Yandulov and R. R. Schrock; Science, 301, 76-78 (2003).

4) "Conventional Lithium Bases as Unconventional Sources of Methyl Anion: Facile Me-Si and Me-C Bond Cleavage in RLi, R 2NLi and BR 4¯ by an Electrophilic Osmium Dihydride," D. V. Yandulov, J. C. Huffman, and K. G. Caulton; Organometallics, 21, 4030-4049 (2002).

5) "Electrophilic (Li+) Acceleration of C-H Reductive Elimination and Oxidative Addition Reactions of Os(II)/Os(0) Nitrosyl Complexes," D. V. Yandulov and K. G. Caulton; New J. Chem., 26, 498-502 (2002).

6) "Structural Distortions in mer-M(H) 3(NO)L 2 (M = Ru, Os) and Their Influence on Intramolecular Fluxionality and Quantum Exchange Coupling," D. V. Yandulov, D. Huang, J. C. Huffman, and K. G. Caulton; Inorg. Chem., 39, 1919-1932 (2000).