Pincer-type ligands, complexes, and catalyst design

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Organometallic chemistry of transition metals (TM) is arguably one of the central areas of modern science owing to the application of TM complexes in catalytic organic syntheses of petrochemicals, pharmaceuticals, and chemicals for agricultural and food industries. The research proposed in this NSERC Discovery grant application addresses several important and challenging types of homogeneously catalyzed reactions. Part (a) seeks to develop chiral PNN ligands from natural amino acids. We will make a family of chiral PNN pincer-type complexes of four metals (Re, Ru, Os, and Ir) for asymmetric hydrogenation of polar C=O and C=N bonds and production of chiral alcohols and amines. Complexes of this type can also be useful for catalytic reduction of esters and amides. Part (b) deals with the development of novel PCP and PCN carbene ligands incorporating a central pyridylidene (rNHC) fragment. Our computational data predict that such ligands should act as exceptionally powerful electron donors when forming pincer-type complexes. These complexes of Ru, Os, Rh, and Ir will be applied in catalytic C-H and N-H bond activation, dehydrogenative coupling, and dehydrogenation and functionalization reactions of hydrocarbons. The PCP and PCN pincer carbene complexes will be explored for nitrogen hydrogenation in an effort to enhance existing ammonia technology and develop new state-of-the-art TM-based catalysts. The proposed research presents an excellent opportunity for training of undergraduate and graduate students in organo-transition metal chemistry, main-group and organic synthesis, catalysis, and computational chemistry.